[330] Phil. Trans., cxliii., p. 368, 1853.
[331] The principle of achromatism was discovered (by Fraunhofer) and achromatic microscopes introduced in the early part of the 19th century. The use of chemical reagents, such as acetic acid, and various hardening fluids, came into fashion not long after. J. Müller seems to have been one of the first to realise their importance. Remak himself invented one or two fixing and hardening mixtures (pp. 87, 127, 1855), which enabled him to cut excellent hand sections. Section-cutting machines were not invented till later (V. Hensen, 1866, His, 1870).
[332] Untersuchungen über die Entwickelung der Wirbelthiere, folio, pp. xxxvii + 195, 12 plates, Berlin, 1850-1855.
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 true that the noticeable resemblances of animals to one another, the possibility of arranging them in a system, the vague perception of an all-pervading plan of structure, did suggest to many minds the thought that systematic affinities might be due to blood-relationship. Thus Leibniz considered that the cat tribe might possibly be descended from a common ancestor,[333] and another great philosopher, Immanuel Kant, was led by his perception of the unity of type to suggest as possible the derivation of the whole organic realm from one parent form, or even ultimately from inorganic matter. In the course of his masterly discussion of mechanism and teleology,[334] he writes, "The agreement of so many genera of animals in a certain common schema, which appears to be fundamental not only in the structure of their bones, but also in the disposition of their remaining parts—so that with an admirable simplicity of original outline, a great variety of species has been produced by the shortening of one member and the lengthening of another, the involution of this part and the evolution of that—allows a ray of hope, however faint, to penetrate into our minds, that here something may be accomplished by the aid of the principle of the mechanism of Nature (without which there can be no natural science in general). This analogy of forms, which with all their differences seem to have been produced according to a common original type, strengthens our suspicions of an actual relationship between them in their production from a common parent, through the gradual approximation of one animal-genus to another—from those in which the principle of purposes seems to be best authenticated, i.e., from man down to the polype, and again from this down to mosses and lichens, and finally to the lowest stage of Nature noticeable by us, viz., to crude matter."[335]
So, too, Buffon's evolutionism was suggested by his study of the structural affinities of animals, and Erasmus Darwin in his Zoonomia (1794) brought forward as one of the strongest proofs of evolution, "the essential unity of plan in all warm-blooded animals."[336]