The Twelve Groups of Animals

Eugen Kolisko, M.D.

“The primary division of the animal kingdom is into phyla. Each phylum is sharply characterised by the possession of a plan of structure in the adult which is peculiar to it, differing from that proper to every other phylum in such ways that it is, in general, incapable of derivation from any other.” (From an article on Zoology in the 14th Edition of the Encyclopaedia Britannica.) If we compare all the different systems of the animal kingdom we find that the distinction between the Vertebrates and the Invertebrates (animals with and without backbones) always occurs. In all the systems too, the Vertebrates are divided into five classes, the whole group being treated as one phylum.

In the Invertebrates there are divisions into phyla, and both Haeckel and Huxley described this group as consisting of seven phyla. These two zoologists differed in their descriptions of any one phylum, but were agreed on the sevenfold division

It appears that we need something in the nature of a key in order to be able to approach the door of understanding of the animal kingdom. The key turns out to be the arrangement of the animals in twelve main divisions or phyla. Seven of them embrace the totality of the Invertebrate Sub-Kingdom. These animals have a soft body and no real skeleton. They are the left-overs of a stage of World- evolution in which the endoskeleton had not been reached. The five phyla of the Vertebrates show the five ways in which the true skeleton can be manifested.

Thus the best way is to describe the characteristic qualities of the twelve phyla or groups in order that the reader may be aware of the archetypal forms of the animal kingdom.

1. The PROTOZOA (animals consisting of a single cell) are the primitive form of organic life, but nevertheless they embrace, in a microscopic appearance, nearly every macroscopic being in all the Kingdoms of Nature. Plants and animals consist in their bodies of cells, and even in the Mineral Kingdom the crystals can be compared with a mineralised cellular structure. Because plants and animals are composed of cells, in the Protozoan group there is no sharp dividing line between the plant and animal kingdom. The great difference between Protozoa (animals consisting of one cell) and Metazoa (all the organisms consisting of many cells) arises from the opposite tendencies of division and cohesion.

In no living organism is it possible to think of the body or soma as being merely the sum total of all the cells—rather has the life of the cell an antagonistic tendency to the metazoic life. This is shown in all infectious diseases caused by Bacteria and Protozoa, because they have in themselves the power of disintegration of the life of the higher organisms. In cancer and other tumours, and especially the malignant tumours, this tendency of the single cell to grow and increase takes place at the expense of the higher organ. In cancer it is not separate and individual cells which cause the disease, but the too-great multiplication of the cells of a tissue. A normal cellular activity becomes malignant in the human being. For this reason no bacterium can be found in cancer.

There is no possibility for further evolution for the Protozoa. They are left-overs in the march of evolution. This class of animals can be thought of as having created all the forms of organic life, by remaining in cellular form in the tissues. But if they appear without the power of further development, they bear in themselves the powers of destruc­tion of all higher life.

2. The COELENTERATA—hydra polyps and medusae (animals such as sea anemones and those which build coral) and all the sponges (which were included in this group in all the older classifications) are characterised by the polarity between the inside and the outside of the organism. These animals are composed of two layers of tissue, the endoderm and the ectoderm (literally, the inner skin and the outer skin). The basic plan of these animals is a cup, the outer layer of which is formed by the ectoderm and the inner by the endoderm. The different species show variations of this plan, as for instance, the beautiful fringe of tentacles around the rim of the cup of the sea anemone. In this group we find for the first time the formation of inner organs. The differentiation begins between the digestive and the nervous system, the latter forming the outer layer.

Haeckel applied his knowledge of embryology (the study of development of living organisms from their earliest rudiments) to his study of the phylum, and by this means he realised that that stage in embryonic evolution in which the embryo loses its spherical shape in order to form something like a cup, and is called a gastrula, can be compared with an adult hydra. These animals are free-living beings corres­ponding to the gastrula stage of embryonic life.

At this point in evolution, the difference between the animal and vegetable kingdoms becomes evident. Those animals which are fixed to the substratum can, however, be thought of as being similar to plants. In this group there may be seen a characteristic dualism which leads to the double generative forms of polyps and medusae. In some species these two forms alternate. In one class of the Coelenterata, the sponges, sea anemones and corals, the polypus-form only is developed, and it leads to a fixed mode of life and then to a plant-like, vegetative growth and solidification. A great part of the solid earth is formed by the deposits of such organisms as rocks (coral rocks, lime­stone, etc.).

The other path of evolution leads to mobility, to soft and pliable tissues, to sexual differentiation and a more animal-like condition. The summit of this is reached in the floating colonies of medusae (soft beings rather like jellyfish in form, and stacked up on one another rather like a stack of plates) colonies where the polypus generation is under the direction of a highly developed medusa. Such a medusa is transformed into an air-bladder and causes the whole colony to float. It is interesting to compare these organisms with the plant. The corals, which become permeated with mineral substance, correspond to the root organisation. The floating colony is more like a blossom, and the intermediate forms of hydra are more like leaves. So we find the dualism appearing in the anatomical structure, in the endoderm and ectoderm, in the digestive and nervous systems (in the functions of digestion and perception) and in the polarity of polyps and medusae, and also in the division of the species into a coral type, in fixed and floating colonies.

3. The ECHINODERMATA (star fishes, sea urchins and sea cucumbers) differ from the previous group by the formation of three layers of tissue. Between the endoderm and the ectoderm may be found the mesoderm. In Coelenterata the whole substance of the animal is absorbed in the formation of the digestive tube. Nothing is left from which other systems or organs might be formed. In the Echinodermata there appears a special system of circulation, the ambulacral system. It combines the functions of blood circulation and movement. The “feet,” which are filled from the ambulacral system, are used for locomotion. Instead of blood, there is sea water; so that the circulatory system is fed from outside. This origin of the system explains the great similarity between sea water and blood, and for this reason all medical injections have to be prepared in a saline solution. So we can see how the outer world, by entering into the animal body gives the basis for further evolution. If the animals had remained in the gastrula stage (i.e. at the level of the Coelenterata) they would not have been able to evolve any true internal organs (i.e. those created within the coelom or body cavity) beside the digestive tract. So the Echinod­ermata have three systems—a nervous system with ganglia, (the enlarged globules of nervous tissue found at various points along the nerves) the first traces of a sympathetic nervous system, a rhythmic or ambulacral system, and a digestive system. It is very interesting that the functions of blood, motion and locomotion are united in the beginning. Limbs and blood vessels are identical, because the so-called feet of these animals are actually organs of locomotion, while at the same time they are filled out with the sacs containing the ambulacral fluid.

A great character of Echinodermata is their radial symmetry. The five rays give a form related to the pentagon.

The star fish has five “arms.” On the extremities of each arm there is an eye. The digestive tract has five sacs, the so-called “livers.” The nervous system has the shape of a five-fold star. The skeleton of the mouth consists of mul­tiples of five teeth—the so-called Lantern of Aristotle. The sea urchin can be understood as a metamorphosis of the star fish when the five arms are closed like the five fingers of a clenched hand. The five eyes are then around the mouth. There are also asymmetrical sea urchins in which the mouth comes to the front and the excretory orifice to the back. Here one can see the beginning of bilateral symmetry as a farther development of the radial symmetry. The animal tendency to produce front and back arises in this way. In the sea cucumbers this is completed. These animals resemble the worms but the radial symmetry can still be seen in five coloured ridges where the suckers are situated. One can imagine the five rays of a star fish being curved back in the opposite direction from that of the sea urchin and then one has the forms of the antidons and sea lilies, which are fixed to the substratum. This idea of a metamorphosis is not put forward as a picture of the real evolution but rather as a description of the relationship between the forms. The real evolution seems to have taken place as a development from a bilateral larval stage (which is common to all echinoderms) to the different formations of radial symmetry.

4. The fourth phylum, the TUNICATA, in which is included the sea squirts, and the salpae, is not very well known to the lay reader, and yet it contains very important representatives in the scheme of evolution. These tunicate animals are generally free swimming, and in form something like primitive fishes. From an external examination there appear to be many similarities with the Coelenterata. There is an alternation of generations between the fixed and mobile forms. The sea squirts have evolved the sedentary way of life and the salpae the mobile one. They correspond with the hydra and medusae respectively, and in both groups there are colonies too. The most peculiar quality of this group is that the embryonic development has a greater significance than the adult form. The young forms are quite similar to the embryos of the fishes and of human beings. One might say that the ideas of Haeckel are based specially on these facts. We have here an animal group which produces the same form in the embryo as do all the higher animals and the human being. It indicates that they are the remains of a process of evolution closely allied to that of the human being, only they have fallen back in their own evolu­tion as animals into a quite early stage. Such an example indicates that all phases of animal evolution express stages of human evolution, but they also lead away from it through falling away into comparative decadence. In the Protozoa the system of the cell falls out as a type from the advancing evolution: in the Coelenterata the mere digestive system does, in the Echinodermata, the circulatory system (fed from the external world) and the tunicates, show the falling away from the later part of the embryonic processes. In the three first groups we had the successive evolution of the three main layers of tissue. In the fourth group we find that the three are combined to give the archetype of all embryological evolution. There exists one very character­istic form of primeval fish, the Lancelet. It resembles very much the growth forms of the sea squirts and salpae. The Lancelet can be considered as a salpae or sea squirt which has remained for its whole life in the embryonic form. It is a primaeval fish. For the fourth phylum brings us to a first stage of perfection (the embryonic) in the animal kingdom.

5. The MOLLUSCA (shell fish, jelly fish and snails) are characterised by a soft body and a hard calcareous shell. A great part of the lime-bearing rocks of the earth are due to the deposits of this phylum of animals. A separation in the mineral substance takes place — all the calcareous salts are drawn to the surface, and the albuminous is drawn to the inner organs. The mantle, the fine membrane lining the shell, indicates the limit between these two processes.

The Mollusca are divided into three distinct classes—the Cephalopoda, or jelly fish, the Acephala or shell-fish, and the Gastropoda or snails. In each of the three classes of this phylum there may be found one of the three systems of the human body accentuated in its development. In the first group, the Cephalopoda, the eyes and the nervous system are very highly developed. The eye of the jelly fish is the most perfect that can be found in the Invertebrata. In the shell­fish the respiratory system is more developed. A shell consists of layers like the pages of a book, and these are the foreshadowing of the gills of the true fishes. In the snails the digestive and reproductive systems are more accentuated in development. The inner organs in their specialisation here appear for the first time. There are not many molluscs without shells. The fossil forms, the ammonites, prove that the jelly-fishes once had shells but subsequently lost them in their evolution. There are even two recent forms known with shells, the nautillus and the paper nautillus. There are three types of shell, the ammonite, the shell of the shell-fish proper and the shell of the snail.

These three types of shell can be correlated with the three directions in space.

The molluscs show by their differentiation that animals represent, in the form of their organisms, the same construc­tive forces as those found in the human organs, but developed in a one-sided way. What in the human being is balanced and in full harmony, appears in the animals in such a way that one organ overwhelms the others and gives the whole character to the being which it forms. Thus, what is a part of the human being becomes an independent being in the animal kingdom. So the jelly-fish represents those parts of the human head which are exaggerated and adapted to a free- swimming form of life. The production of the sepia pigment is comparable with the production of saliva. For this reason, Lorenz Oken compared the jelly-fish with the human tongue.

The shell-fish proper create pearls and mother-of-pearl. In every shell-fish there exists, between the mantle and the shell, a layer of mother-of-pearl. The pearls appear between the two spheres separated by the mantle—i.e., the salt and the albumen spheres. If these meet each other, or a third entity similar to one meets the other (e.g., a grain of sand) then a pearl is formed and unites in itself the translucence of the salt and the opaqueness of the albumen. So the pearl appears like a precious stone from the animal kingdom.

The snails produce certain pigments, as, for example, the Tyrian purple. There is a connection between their metabolism and the production of this pigment. The purple pigment is brom-indigo, a compound of bromine and indigo. The indigo contains nitrogen and is produced from the albuminous processes. The bromine is taken from the bromine salts in the sea water. The purple snail synthesises these two substances—a process we have learned to imitate in our manufacturing processes. This purple, produced by the metabolic processes of the snail, is one of the strongest of the blue dyes, while bromine is well known as an element of an intensive reddish colour. By the fusion of these substances, purple is formed and is an interesting example of Goethe’s theory of colour, in which he stated that purple was to be explained as the mixture of red and blue.

There is more than an accidental affinity between the molluscs and the substance lime. The carbon-dioxide, a product of the exhaling of the animals, combined with the calcium, forms the main constituent of the shell. So the shells may be thought of as the petrified exhalations of the molluscs.

6. In the VERMES or worms the most characteristic feature is the segmentation of the body. It only appears in its full perfection in the class Annelidae (especially the earth­worms), but it is understandable that a group can best be studied from the characteristics of its most highly developed members rather than from the less highly evolved forms. The whole phylum can be regarded as a graduated development in which the first stages have been left behind and form the most primitive members of the group. There exists ordinarily no shell, but the same forces which produce shells in the molluscs are set free in such an organism as the earthworm and work in the surroundings of the animal. So the earth­worm is endowed with the faculty of transforming soil into humus. As Darwin has proved in his book on the earthworms, the formation of the fertile humus is due to the work of this highest class of the Vermes phylum. Thus the molluscs form some of the solid limestone deposits of the earth, while the worms work to produce fertility in the earth and thus minister to the growth of vegetation. There can be no vegetation without earthworms.

In the worms the digestive system is the most highly developed. These animals may be considered as free-living intestines, and, in fact, the movement of an earthworm is quite similar to the peristaltic movement of the intestines. In the Annelidae there exists blood with haemoglobin to some extent similar to the mammalian and human blood. All the lower classes of the Vermes are comparatively very imperfect, and they often descend to parasitism. The earthworm is the summit of the evolution of the group—many other represent­atives live in the sea and are often transformed into very beautiful vegetative forms. Many more have fallen into a parasitic form of life and live in other animal organisms and in man. It is specially the digestive system of the higher animals and man that is predisposed to the Vermes influence. One can understand this readily if one thinks of a worm as an independent digestive system. Being themselves free-living digestive organs, they can easily live in other digestive systems. This explains many riddles, such as the tape-worms and the appearance of trichines (a certain species of worm) in pigs. As a general rule parasitism cannot take place without an inner relationship between the parasite and its environment. The most interesting example of parasitism in the Vermes is the leech. It is very near to the earthworm, but it has fallen into parasitism, and instead of giving life to the earth and its vegetation, it sucks up the blood—the central vehicle of the life of the human being. There is an anti-coagulating reagent in the saliva of the leech, which enables the blood of the victim to pass in a fluid condition into the parasite. The substance of calcium gives to the blood the stimulus to coagulation. In the Annelidae the albuminous, anti-coag­ulating force is more developed. There is a polarity between the production of salt-containing shells and that of albuminous substance, that which always prevents coagulation.

7. The ARTHROPODA (Insects, centipedes, spiders and the crab tribe), and especially the insects, are character­ised by the division of the organism into sharply defined parts, in contradistinction to the almost endless segmentation of the worms. The respiration is highly developed, in contrast to the worms where the digestion is the salient feature. The insects are the most characteristic class, but there are three others, giving the four main classes as follows:—Insecta, Myriapoda, (centipedes, etc.) Arachnidae (spiders) and Crustacea (crabs, etc.).

In the insects there is a very clear distinction between the three main parts of the body—the head, thorax and abdomen. The legs are attached to the middle part, the thorax, and there are always three pairs (hence their name, Hexapoda). The insects also have a pair of antennae or feelers and three pairs of mandibles or ” jaws,” giving seven pairs of extremities in all. The skin is transformed into a hard sheath of chitin, a substance very near to cellulose in its composition. Cellulose is the substance from which the cell walls are made in plants, and the relationship between the cell wall and the chitinous sheath is one of many, appearing between the two kingdoms in this group. Just as there are three divisions to the body, so there are four separate stages in growth. This animal metamorphosis consists in the development from the egg, to the larva, or grub, then to the cocoon and finally to the perfect insect. As in the worms everything flows in waves, so in the insects everything is divided into parts. This may be seen further in the formation of colonies, where every individual insect is separate from the others, but from the functional point of view they form an unity. Everything is divided up in this group—the body in space, the development in time, and the colonies in organisation. There are also innumerable species so that even in this direction the division is manifold. The insects are the most highly developed and characteristic class of the Arthropoda.

All scientists acknowledge the fact that the insects are extreme branches of biological evolution, and this is the reason for the extreme perfection of their colonies and life. Thus nobody ever supposes them to have played an important part in the ancestry of the mammals or of man. On the other hand there are innumerable connections between them and the plant kingdom. As Rudolf Steiner has discovered, the metamorphosis of the insects has a deep connection with plant growth. The plant develops from the seed to the leaf-bearing stage, the bud stage, and finally the blossom. As Goethe has indicated in detail, these stages are inter­changing contractions and expansions. In the insect there are also four stages, but each stage arises as a metamorphosis of the previous one and is independent of it, evens as regards locomotion. There is a deep inner connection between the insects and the plants. The insects are really a repetition of the flowering plants in the animal kingdom. The mutual correspondence between insects and plants, as, for example, those between butterflies and bees on the one hand and the blossoms on the other, can easily be understood when we know that the blossom is a butterfly which has no locomotion, and the butterfly is a flying blossom. The idea may seem strange and abrupt, but if we consider that most flowers cannot accomplish their fructification without the assistance of certain insects, then it becomes evident that these insects must not be considered as separate individuals, but really as part of the plant kingdom. That they are movable should not prevent our recognising the fact that the flowers form one organism which includes all those insects which cooperate with them. This theory will also explain mimicry. That locust which is called ” the walking leaf ” does not take the shape of a leaf because it imitates the leaf, but such locusts have the inner structure of the leaves they appear to copy. All mimicry must be explained by an inner relation between the two organisms concerned. The leaf mantis unites the formative powers of the plant kingdom with the organisation of animals. It is interesting, too, that the insects are as dependent upon the seasons and the daily position of the sun as are the plants. They form one great body, together with the vegetation of the higher land plants.

In describing later the higher animals, we shall see that three great groups exist, the birds, the carnivorous mam­malia, and the herbivorous mammalia. In the insects we have the butterflies which can be compared with the birds. The bees are the lions, the wasps the tigers and the bumble bees the bears. One can see how certain formative forces of the animal kingdom work differently in the different groups. The beetles can be compared with the ruminants. All the ruminant forms reappear in the beetles, even to the names, as for example the stag-beetle which follows the organisation of the deer. The three groups of insects already named have followed a perfect evolution. The other groups such as locusts, dragon flies, etc., have not accomplished a perfect evolution and the great tody ol noxious insects show, by their mode of life, that they have deviated from the real path of insect life.

In the other classes of the Arthropoda, the Myriapods show relationships to the worms. The spiders are in an intermediate stage between the insects and the crabs. The number of legs increases from six to eight. In the Crustacea may be found animals ranging from tiny microscopic forms to others of considerable dimensions (crabs, lobsters, etc.). Although they have the structure of Arthropods they live in water. Many of them have chitinous armour and some of them live together with shell fish and other similar creatures from the lower phyla of the animal kingdom.

In the crustaceans we can follow a retrograde path of evolution back from the insect stage, back through all the intervening stages to an existence which is comparable with that of the Protozoa. Thus the Arthropoda are the highest group of the invertebrates and the crustaceans in their retrograde evolution repeat in an inverse direction all the previous stages of evolution.

8. The VERTEBRATA. Fishes are the first phylum of the vertebrata. Here we have the endoskeleton, proceeding from a vertebral column which surrounds a cerebro-spinal system. The invertebrata have only a sympathetic nervous system with ganglia and no endoskeleton. The formation of the spinal cord and the vertebral column go hand in hand. The fishes are the organisms which are best adapted to the watery element. There is no water without fish. They are very dependent on all the currents of the water, on the seasons, and on the whole life of the ocean and rivers. In the upper layers of the ocean and in fresh water we find the ordinary forms such as the herring and the trout. Quite different are the forms of the deep-sea fishes. They are really the remains of a previous epoch. They have a carti­laginous skeleton and quite extraordinary forms. The rays, sharks, and dogfish belong to this type, though they are not deep-water fishes.

It is interesting that in the phylum of the fishes there is an immense variety of forms but a clearly marked uniformity of type. They are the phylum where the animal life, which in its first stages is always connected with the ocean, comes to the highest perfection attainable in the watery element. With a few exceptions they have no possibilities of life in the air element. The fish can be considered as a most accomplished rhythmical organism. It corresponds to the trunk of the human body. The head and limbs are not much developed. The sense organs are spread out over the whole organism, as, for example, the organ of equilibrium, which is, in’ the human being, located in the ear. In the fish it extends along the back, and is indicated by a dark line along the surface. There is also a correspondence between the iris of the fish’s eye and the glistening scales of its body. The enamel of the teeth is spread out over the whole body in the scales. The adaptation of the colour of the outer surface of the fish to the colour of the substratum depends on its faculty of sight. Blind fishes cannot adapt themselves to the colour of their surroundings. So all the functions of the head of the higher animals are spread out over the whole body of the fish.

Because the fish is predominantly a rhythmical system, it is very sensitive to the rhythms of the water. It does not hear tones with its ear but is sensitive to vibrations all over its body. It has no sense of taste in its mouth, but can “taste” the concentration of the salt with its whole skin, and by this perception regulate its movements accordingly, for the salt varies with the depth of the ocean.

The fishes have immense reproductive forces and produce many more eggs than are necessary for the perpetuation of the species. These eggs serve as food for other organisms, especially other fishes, and the larger prey upon the smaller. In the fish group reproduction and nutrition go hand in hand, and the sum total of all the species forms a whole, because the surplus from the one process supplies the need of the other. This use of the superfluous forces of reproduction for the demands of nutrition is not found in any other phylum.

9. The AMPHIBIA (the frog tribe) make a great step forward in animal evolution. They are the first to evolve true limbs in conjunction with an endoskeleton. The limbs of the insects cannot be compared with these organs. The amphibians are the first vertebrate animals to proceed to life on the solid ground. Respiration adapts itself to the atmosphere and lungs replace gills. There is a connection between the formation of lungs and the formation of limbs. The oxygen inhaled by the lungs is used in those combustion processes which enable the limbs to move. This is seen very clearly in the metamorphosis of a tadpole into a frog. The involution of the lung corresponds to the evolution of the limbs. In the metamorphosis of the tadpole one can see the transformation of an organism with gills and tail into one with lungs and limbs.

Voice, smell, and hearing now appear in the Amphibia for the first time as an adaptation to life in the atmosphere. The fish is deaf and mute; the frog hears and croaks. In the fishes reproduction takes place completely outside the individual. The eggs and the sperm meet in the water and the sun gives warmth for the growth of the young. In the Amphibia reproduction comes about by a primitive sort of copulation. There is a similar condition to that of the molluscs in so far as the organism remains comparatively soft, pliable, and to some extent unformed.

10. The REPTILIA (snakes, lizards, etc.) all have lungs throughout their lives. Here again there is segmentation of the body and a tendency to shorten the limbs. In snakes the limbs are invisible, although traces of their bones remain in the skeleton, especially during embryonic development. The digestive system is the most developed. As molluscs have a certain con­nection with the Amphibia by reason of their general softness and lack of form, this is also the case with regard to reptiles and worms. A snake is, as it were, a vertebrate worm. The digestive system has enormous vitality; the nervous system is not much developed. This vitality can also be seen in the faculty of regeneration, which is very strong, especially in tortoises. Reptiles live more in the tropical belt of the earth. They need the warmth of the sun for hatching their eggs. Their blood is not warm but fluctuating in temperature. The longitudinal division of the heart is not quite perfect. Their immense vitality is in inverse proportion to their intelligence. The human will- forces are similarly vital, and when they come into relation with this animal vital force they can have a repelling power. A well- known example is the power of the Oriental snake-charmer. As music has a strong influence on the human will, so all reptiles can be fascinated by it. The instinctive antipathy of the human race for this group of animals can be explained by the fact that our moral and intellectual development has been accomplished in opposition to those forces of the vital system which are one-sidedly developed in this phylum.

The snake has lost the capacity for voice production, which is connected with the formation of limbs. Both have been sup­pressed. Only one sound, the Ssss sound, which is connected with the sinuous S shape of the body in its movements, has remained. The snake gives one the impression of a being in which the forces of the voice have been dissipated and find no adequate limbs in which to express themselves.

There are three classes in the Reptilia: the Saurians (to which belong also the extinct group of the Mesozoic Saurians) or the lizards, the snakes, and the crocodiles. Lizards have a greater development of the nerves and senses. Snakes are the truest type of reptiles, while the crocodiles have developed most of the digestive and limb system. Tortoises are related in many ways with the Amphibia. All the reptile phylum is really only a small remainder of the great Mesozoic Saurian fauna. At that time the animal kingdom had not reached a higher level of development.

11. The BIRDS (with the mammals) are the highest flower of the animal kingdom. They have warm blood which remains at a constant temperature. This is ensured by their two kinds of warm covering, feathers or hair. The feather is created, as its structure shows, from “outside,” and the glistening colours are a response to the light and other forces of the surroundings. They contain silica in great quantities, sometimes as much as 20 per cent of the ash. Birds can only be understood if they are con­sidered in relation to their surrounding atmosphere. They are as well fitted for the air as the fish for the water. The air pene­trates the body even to the bony system, as there is no bone- marrow in the long bones, but air spaces, connected with the lungs. This gives the bird the possibility of flight. Their inner organs are not very well developed, and the digestive organs and the legs especially are reduced. On the other hand, the wings, lungs, and feathers are developed to a very high degree. The most striking attainment of the birds is the yearly migration of certain species. It is carried out with the greatest possible intelligence. This is not the intelligence of the single bird, but a greater intelligence which is in connection with the atmospheric air currents and the constitution of the earth as a whole. The eagle is not only the symbol for the highest flight of human intelligence, but the same forces which work in the human brain in the activity of thinking are also at work in the flight of the eagle and in the formation of its feathers and wings. The whole bird phylum can be compared with the upper part of the human being—the eagle is, as it were, a flying head. The same power which forms the brain in the human being becomes the instrument of flight in the eagle.

There are three great classes of birds: song birds, birds of prey, and the swimming and running birds. The song birds have undergone a further development in the larynx and of the finer organization of the senses. In birds of prey, the forces connected with the wings are the most developed. There is, in these birds, an intense connection between sight and movement, and the faculty of sight is specialized for the perception of moving objects. In the swimming and running birds the digestive system is more developed, and they therefore lose some of their possi­bilities for flight. Parrots, to a certain extent, have developed all the three faculties of senses, rhythm, and digestion, but they appear grotesque because they are a mixture of the three types and have not, as it were, made up their minds which to be. Not one of the three systems is well evolved, but as all three are at work, the parrot resembles the human being in the use of its voice, and because its three systems are still not humanized it appears as a caricature.

There is a certain polarity between the production of eggs and the making of nests in the bird race. Song birds are great artists in nest-building, but the eggs are small, the young are compara­tively unformed and weak and remain for a long time in the nest. On the other hand the running and swimming birds lay big eggs, but their nests are rather sketchy and the young are active and well-developed from the time they are hatched. There is a hidden intelligence in the construction of the nest, but one which proceeds not from the brain but from all the senses. In the nest the bird creates around itself a structure rather like a materialized aura. It collects the materials from its surroundings by the intelligent use of the nervous system and senses, and by flight. The egg is a product of the vital system (which comprises the functions of metabolism and reproduction) and the faculty of producing either more eggs or better nests varies in the different birds. The greater powers of the vital system in the running and swimming birds have a corresponding reduction in the formation of the nests, while the song birds, with their greater sense-activity, are the greatest artists in nest-construction, but their eggs are small and few. The picture of the female bird sitting on her nest gives the completely balanced organism. The forces of the intelligence have created the nest, the warmth of the blood is the salient feature of the brooding mother, and the eggs are the counterpart of the vital system.

12. In the MAMMALIA the animals reach their highest point of perfection. The temperature of the blood is constant, and there is a hairy covering. This is much more connected with the influence of the blood than are feathers. The maintenance of a constant body temperature is mostly due to the hairy coat. The colour of the hairs is not influenced so strongly by the light as are the feathers of the birds, but it is more closely connected with the warmth of the blood. Pigmentation is influenced strongly by the colour of the earth on which the animal lives, as, for example, the polar bear. The animal perceives this colour and is permeated by its influence so far as to reproduce it in the colour of its coat. To the Mammals belong all the fur-bearing quadru­peds, which are really the big animals of the solid earth. Only the mammals have a diaphragm separating the organs of the thorax from those of the abdomen. The recognition of this fact leads to a true systematism of the Mammalia. They may be considered as having two main types, one in which the organs of the thorax are predominantly developed, and the other in which those of the abdomen are. These are the predacious animals and the ruminants respectively, and their allied species. The great distinction between carnivorous and herbivorous animals is largely parallel with these two groups. Either the rhythmical system of the thorax or the digestive system prevails. The lion is the perfect type of the first great class. It has a well- developed blood circulation, but its legs and claws are rounded in form, showing thereby the characteristics of those forces which produce rounded ribs and all the other much-curved forms of the thorax. The muscular system is very well developed and a great elasticity of the tissues indicates the development of the rhythmical system. On the other hand, the ruminants have a long abdomen and four straight limbs with hoofs. All the families of the Mammalia can be fitted into one of these two groups. The cats and the ruminants are the prototypes, but each family has a tendency in either one direction or the other. The lion and the cow are the best representatives of each class. The blood- circulation and the digestion are one-sidedly developed in these two animals. These two types belong to the last fauna to be developed—the post-glacial. In earlier geological times the two types were not so clearly evolved. In an earlier age they appear as the pig and the horse—the pig being nearer to the carnivora and the horse to the ruminants. In the tapir we have the remains of a far earlier evolution—a third stage back. It was the ancestor of the pigs as well as the horses and united in itself the qualities of both these animals. The Ungulates (elephants, rhinoceroses, etc.) are remnants of this or a still earlier time. The elephant has developed more the qualities of the nerves and senses (it has great intelligence and a very keen sense of smell) and the rhinoceros the digestive system.

In the sea mammals we find a similar differentiation, for we have sea-cows and sea-lions. The whale is a counterpart of the cow on the land, and the sword-fish the counterpart of the tiger.

Bats, kangaroos, and the duck-billed platypus belong to a much earlier evolution—even before that of the Tertiary epoch—when the different classes of the Mammalia were not so sharply defined or separated.

Rodents may be considered as an intermediate group between the ruminants and the cats. In the ruminants the molars are more developed than the other teeth. In the cats it is the dog­tooth and those near it which are most prominent, while in the rodents the incisors are the most important. They have a per­petual growth and these animals are forced to wear them down continuously or they would grow so long as to close over the mouth. This explains the perpetual nibbling of the rodents. The forelegs are to some extent free from the earth and help the work of the teeth, so that some of the rodents sit up and “beg.” Some are small and are tree-climbers, and they have some connections with the birds (e.g. bats, which are related to mice). If one includes the Insectivora, then one sees that in the Rodentia there is one type of carnivora (the moles) and one of herbivora (the mice).

The two great types of the mammals, the lion and the cow, form, together with the bird type, the threefold structure of the higher animal kingdom. This enables us to understand how the human being has harmonized these three types in his three systems of nerves, thorax, and abdomen. The eagle, the lion, and the bull can be considered as the three symbols of these types. This was known to an ancient wisdom, and the writers of the Gospels have these animals as their symbols because they tried to give the picture of the perfect human being in his three constituents:

The Bull . The animal with the most perfect digestive system.

The Lion . The animal with the most perfect rhythmical system.

The Eagle . The animal with the most perfect nervous system.

Thus it is now possible to prove by means of modern natural science what was once known by ancient wisdom.

The monkeys and apes have a quite different origin from the other Mammalia. They do not correspond to one of the three types of the higher animal evolution, but they try to unite all three. Not having the full human forces, they fall short of their goal. They have the same harmonizing tendency as the human being but cannot carry it far enough. Therefore they are as different from the other animals as they are from human beings. One-sidedness is characteristic of all the animals. Many-sidedness is characteristic of the human being. The monkeys can only imitate the human being and not reach full human development. It is a similar case to that of the parrots.

There are two main types of the monkey tribe, the monkeys proper which have tails, and the apes which have not. Tailed monkeys are nearer to the rodents, and at the same time to the other animals, while the apes exemplify rather more those characteristics already enumerated for the whole group.

These twelve phyla are the principal groups of the animal kingdom, and give a bird’s-eye view of the whole system. We may say that there are three great steps, with four subdivisions in every step. The first step includes phyla I to 4. These animals, in comparison with the human organism, correspond only to the head, as, for instance, the star-fish, with eyes on the points of the so-called legs. This shows that the whole organism can only be compared with a head.

The next step includes phyla 5 to 8. The thorax is now developed. The fish is the most highly evolved in this direction.

In the third step, phyla 9 to 12, the digestive and limb system is perfected. So we can see animal evolution proceeding from the head-organization to the chest, and then to the metabolic system and limbs. This corresponds very perfectly with the evolution of a single human being. In the embryo the head is first developed, and the other organs follow at a later stage. The question of human evolution will be treated later from this standpoint.

Each of the three great steps takes place in four subdivisions. In the first step, Protozoa, we have the evolution of the cellular system. Then we have:

Protozoa . . Animals with the cellular system developed. Coelenterata . Animals with the digestive system developed. Echinodermata Animals with the rhythmical system developed. Tunicata . . A harmony of all the organs but only in the embryonic stage.

This picture is repeated in the second great step. Here we find:

Mollusca . . Animals in which the reproductive system prevails.

Vermes . . Animals in which the digestive system prevails.

Insecta . . Animals in which the respiratory system prevails.

Pisces . . . Animals in which the blood circulation is developed, and an advance is made towards the evolution of the heart. There is harmony amongst the organs in a higher stage than before.

The third step repeats the divisions as follows

Animals in which the reproductive system is developed.

Animals in which the digestive system is developed. Animals in which the respiratory system is de­veloped.

Animals with a perfect development of the heart, warm blood, and a constant temperature.

If we consider a polyp, a worm, and a snake, we can see the three steps on three different levels. It is a worm type in a primitive phase and in a vertebrate phase, and the true worm is the intermediate phase. Polyp—worm—snake.

The star-fish, insects, and birds are three types of animal in which the respiration is emphasized at different levels.

The stages 4, 8, and 12—Tunicata, Fishes, and Mammalia— mark the points where human evolution has certain connections and which, therefore, appear as successive stages of human embryology. So the archetype of the human being stands behind all these forms and shows that the human form can be considered as the universal form of the animal kingdom.

First published in The Present Age in 1936 under the title “The Classification of The Animal Kingdom”.