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And through the twenty-five years that have passed, since the matter of life was first called protoplasm, a host of investigators, among whom Cohn, Max Schulze, and Kühne must be named as leaders, have accumulated evidence, morphological, physiological, and chemical, in favour of that "immense unité de composition élémentaire dans tous les corps vivants de la nature," into which Payen had, so early, a clear insight.
But the Xiphosura have such close morphological relations with the Arachnida, and especially with the oldest known Arachnidan, Scorpio, that I cannot doubt the existence of a genetic connection between the two groups. On the other hand, the Branchiopoda do, even at the present day, almost pass into the true Podophthalmia, by Nebalia.
We have said that the following out of the properties exhibited by physiological species would lead us into difficulties, and at this point they begin to be obvious; for, if, as a result of spontaneous variation and of selective breeding, the progeny of a common stock may become separated into groups distinguished from one another by constant, not sexual, morphological characters, it is clear that the physiological definition of species is likely to clash with the morphological definition.
C., and that Bacteria, TorulA|, and other infusorial forms, making their appearance in super-heated flasks, originate not from morphological cells, plastide particles, bioplasts, or any other vital organism, but from indestructible vital units, which are everywhere present in the organic matter of our globe, and ready to burgeon forth into life whenever the necessary vital conditions exist, and the proper incidences of environment occur.
No one would hesitate to describe the pouter and the tumbler as distinct species, if they were found fossil, or if their skins and skeletons were imported, as those of exotic wild birds commonly are and without doubt, if considered alone, they are good and distinct morphological species.
Both processes, in their initial stages of development, lie beyond the reach of human scrutiny, and all that we know, or possibly can know, is, that certain inorganic conditions are favorable for the development of crystals, as certain organic conditions are favorable for the development of morphological cells. Beyond this Professor Bastian knows nothing we know nothing.
It is true that these simple laws are not as yet all discovered; but the one great discovery of Phyllotaxis, which shows that all plants follow one law in the arrangement of their leaves upon the stem, thereby intimates in unmistakable language the simplicity and unity of all organic vegetable laws; and a similar assurance is given by the morphological reduction of all parts to a metamorphosed leaf.
Contrariwise, we must suppose that such effect of the medium either was not wrought at all, or that it was evanescent: though repeated through millions upon millions of generations it left no traces. Does any one think this a tenable position? And now we approach the last and chief series of morphological phenomena which must be ascribed to the direct action of environing matters and forces.
We can now say with some reason that “the gulf between the two kingdoms of nature has become deeper just in proportion as our physical and chemical, our morphological and physiological knowledge of the organism has deepened.” Mach’s expression “mechanical mythology,” is quoted, and then a fine passage on the insufficiency of the mathematical view of things in general concludes thus: “Mathematics is only a method of thought, an excellent tool of the human mind, but it is very far from being the case that all thought and knowledge moves in this one direction, and that the content of our minds can ever find exhaustive expression through it alone.”
If we appreciate the full weight of these morphological and physiological facts, and put a proper phylogenetic interpretation on the observations of embryology, we see that the older idea of the personal immortality of the human soul is scientifically untenable.
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