E. S. Russell

“ But one may hazard the opinion that the present century will see a return to a simpler and more humble attitude towards the great and unsolved problems of animal form. Dogmatic materialism and dogmatic theories of evolution have in the past tended to blind us to the complexity and mysteriousness of vital phenomena. We need to look at living things with new eyes and a truer sympathy. We shall then see them as active, living, passionate beings like ourselves, and we shall seek in our morphology to interpret as far as may be their form in terms of their activity. ”

“ The animal feels and perceives its surroundings, reflects its sensations, moves of its own will under their influence, and, as a rule, can communicate by its voice its desires and its fears, its pleasures or its pains. I call organic life the sum of the functions of the former class, for all organised creatures, plants or animals, possess them to a more or less marked degree, and organised structure is the sole condition necessary to their exercise. ”

“ By unity of type is meant that fundamental agreement in structure which we see in organic beings of the same class, and which is quite independent of their habits of life. On my theory, unity of type is explained by unity of descent. The expression of conditions of existence, so often insisted upon by the illustrious Cuvier, is fully embraced by the principle of natural selection. ”

“ The fact that only the structure of man and the higher animals was at all well-known in his time led Goethe to think that his general Typus would hold for the lower animals as well, though it was to be arrived at primarily from a study of the higher animals. All he could assert of the entire animal kingdom was that all animals agreed in having a head, a middle part, and an end part, with their characteristic organs, and that accordingly they might, in this respect at least, be reduced to one common Typus. ”

“ This rational principle, peculiar to natural history, Cuvier calls the principle of the conditions of existence, for the following reason:—"Since nothing can exist that does not fulfil the conditions which render its existence possible, the different parts of each being must be co-ordinated in such a way as to render possible the existence of the being as a whole, not only in itself, but also in its relations with other beings, and the analysis of these conditions often leads to general laws which are as certain as those which are derived from calculation or from experiment." ”

“ In Morphology we should not speak of Gestalt or fixed form, or if we do we should understand by it only a momentary phase of Bildung. Form is of interest not in itself but only as the manifestation of the inner activity of the living being. Over development, he says elsewhere, there presides a formative force, a bildende Kraft or Bildungstrieb, which works out the idea of the organism. Living things, in his view of them, strive to manifest an idea. They are Nature's works of art—and so, incidentally, they require an artist to interpret them. ”

“ The main systems of organs are, in order of importance, the nervous and muscular, the digestive, the circulatory, and the respiratory. Each organ or system of organs may have many forms. If any form of any organ could exist in combination with any form of all the others there would be an enormous number of combinations theoretically possible. But these combinations do not all exist in Nature, for organs are not merely assembled (rapprochés) , but act upon one another, and act all together for a common end. ”

“ The biogenetic law went beyond both the Meckel-Serres law and the law of von Baer in that it recognised that the ancestral history of the species accounts in part for the course which the development of the individual takes, that in a certain sense, though not in the crude way supposed by Haeckel, phylogeny is the cause of ontogeny. This thought, that the organism is before all an historical being, is of course implied in the evolution idea, is indeed the essential core of it. ”

“ We tend also to lay the causes of form-change, of evolution, as far as possible outside the living organism. With Darwin we seek the transforming factors in the environment rather than within the organism itself. We fight shy of the Lamarckian conception that the living thing obscurely works out its own salvation by blind and instinctive effort. We like to think of organisms as machines, as passive inventions [457] gradually perfected from generation to generation by some external agency, by environment or by natural selection, or what you will. ”

“ But what then is the true relation between the variety of development and the variety of adult structure? Before answering this question we must review the varied forms of adult organisation and consider in what relations they stand to one another. In particular we must enquire whether they belong to one type or to many. One point is here cardinal—we must distinguish between the type of organisation and the grade of differentiation. By "type" von Baer means the structural plan of the organism. "I call the type the spatial relationship of the organic elements and organs" (p. 208) . ”

“ CHAPTER XIII THE RELATION OF LAMARCK AND DARWIN TO MORPHOLOGY.
It is a remarkable fact that morphology took but a very little part in the formation of evolution-theory. When one remembers what powerful arguments for evolution can be drawn from such facts as the unity of plan and composition and the law of parallelism, one is astonished to find that it was not the morphologists at all who founded the theory of evolution. ”

“ It is sufficiently clear from this quotation that Geoffroy was thinking only of a transformation of the antediluvian species created by God, and by no means of an evolution of all species from one primitive type. In matters of religion Geoffroy was orthodox. He goes on to point out how great a resemblance there is in essential structure between fossil and living species. All find their place in one scheme of classification; does it not seem that all are modifications "of one single being, of that abstract being or common type, which it is always possible to denote by the same name?" ”

“ Pure morphology is essentially a science of comparison which seeks to disentangle the unity hidden beneath the diversity of organic form. It is not immediately concerned with the causes of organic diversity—that is rather the task of the sciences of the individual, heredity and development. To take an example—the recapitulation theory may legitimately be used as a law of pure morphology, as stating the abstract relation of ontogeny to phylogeny, and the probable line of descent of any organism may be deduced from it, as a mere matter of the ideal derivation of one form from another ”

“ The embryo of a mammal resembles in many points, at different stages of its development, the adult state of a fish; it has gill-slits and complete aortic arches, a two-chambered heart, and so on. But at no time does it combine all the essential characters of a fish; nor has it ever the tail of a fish, nor the fins, nor the shape. Any recapitulation there may be is a recapitulation of single organs, there is never a repetition of the complete organisation of a fish. This is indeed the fundamental criticism of the theory of parallelism ”

“ Homology is still determined by position, by connections, in the embryo as in the adult. "Similarity of development" has become the criterion of homology in the eyes of the embryologist, but "similarity of development" means, not identity of histological differentiation, but similarity of connections throughout the course of development. For the purposes of morphology, development has to be considered as an orderly sequence of successive forms, not in its real nature as a process essentially continuous. Morphology has to replace the living continuity by a kinematographic succession of stages. ”

“ Since function comes before form there is not always a special organ for every function. "It is a grave error to believe that a particular function can be performed only by one and the same organ. Nature can arrive at the desired result by various ways, and when we look down through the animal kingdom from the highest to the lowest forms we see that the function does not disappear even when the special instrument provided for the purpose in the higher types ceases to exist" (p 470) . ”

“ One might almost say that the plant is the framework, the foundation of the animal, and that to form the animal it sufficed to cover this foundation with a system of organs fitted to establish relations with the world outside. It follows that the functions of the animal form two quite distinct classes. One class consists in a continual succession of assimilation and excretion; through these functions the animal incessantly transforms into its own substance the molecules of surrounding bodies, later to reject these molecules when they have become heterogeneous to it. ”

“ Aristotle was much struck with certain facts of correlation, of the interdependence of two organs which are not apparently in functional dependence on one another. Such correlation may be positive or negative; the presence of one organ may either entail the presence of the other, or it may entail its absence. Aristotle has various ways of explaining facts of correlation. He observed that no animal has both tusks and horns, but this fact could easily be explained on the principle that Nature never makes anything superfluous or in vain. ”