The two great phylogenetic theories having failed, the question may arise whether the whole theory of descent is not simply a great illusion. But that is very far from being true. We are merely obliged to search for other hypothetical phylogenetic principles.
Lamarck himself, as we have mentioned already, was not blind to the fact that a sort of organisatory law must be at the base of all transformism, and it is well known that hypothetical statements about an original law of phylogeny have been attempted by Nägeli, Kölliker, Wigand, Eimer, and many others. But a full discussion of all these “laws” would hardly help us much in our theoretical endeavour, as all of them, it must be confessed, do little more than state the mere fact that some unknown principle of organisation must have been at work in phylogeny, if we are to accept the theory of descent at all.
We shall ourselves, therefore, attempt nothing more than to establish the chief phylogenetic problems.
And in this respect the first question is, no doubt, whether or not organic life in its totality may be regarded as one great whole of super-personal character.
And there are four indexes of wholeness in organic life, so it seems to me:
First, the fact of propagation, i.e. the active formation of new starting-points of individual morphogenesis on the part of all organisms.
Secondly: the existence of the organic system, i.e. the fact that the totality of living forms is not chaotic.
Thirdly: the existence of so-called analogies, strongly emphasised by Bergson, i.e. of very similar organs in forms which have no systematic relations. Think of the eyes of vertebrates and cuttle-fishes.
Fourthly: all mutual adaptedness, as among plants and insects, among gall-forming insects and their hosts.
The second great question is, whether phylogeny is a real evolution, and not a mere contingent cumulation as the so-called geological “evolution” of the earth certainly is. These concepts will be fully explained in the philosophical part, and we only note in this place that the embryological process is the very prototype of what we mean by “evolution”
The answer may be in the affirmative here also, first, because the contingency theories of Darwin and Lamarck have failed; this, of course, is a negative argument. And, secondly, because a good many palaeontological lines of forms show us something like a specific direction.
But even if, in this way, the process of phylogeny may appear as one great super-embryology, the differences between phylogeny and embryology must not be overlooked.
Embryology ends in the formation of one thing. The phylogenetic process manifests itself in many things. And the spatial and temporal relations among them, the hic et nunc of the individuals, to use the scholastic phrase, is contingent. Only the quality, the essentia, is important.
And, further: embryology occurs in many cases, whilst there is only one phylogeny (of which we ourselves are a part!). This, in fact, is the ultimate reason of our ignorance in phylogenetic questions. We cannot make experiments with “the” phylogeny, and therefore we know nothing of its law. We do not even know what the “end” of phylogeny is, and whether the end has already been reached or not. Simply to say that man is the end, would be very egotistic. There are probably many “ends”.
Are the individuals organs of a super-person, comparable to the organs of an individual? Then they should accomplish a “function” with regard to that super-person. What function? We are ignorant.
But let us stop here, though the list might easily be continued; and let us, at the end of all, only state two more problems, in the form of questions:
What does it mean to say that a certain species has died out, as, e.g., many great reptilia have? Does it mean that they really have died without offspring? Or that they have been transformed into a higher type? Steinmann and Dacqué have raised this question.
And is the polyphyletic or the monophyletic theory true? If the first were true, then the “amoebae,” as we may call them, of primordial ages would not all have been real “amoebae”; but some of them would have been potential vertebrates, others potential arthropods and so on.
What, finally, about the coexistence of very highly developed and of very primitive creatures in our present days? Why have the latter remained “primitive”?
Again—the list of questions is far from being complete.
But there are no answers.1
We strongly recommend the study of two valuable books: J. A. Thomson, The System of Animate Nature, and J. C. Smuts, Holism. Lloyd Morgan’s Emergent Evolution is also very suggestive. Comp. also the discussion on “Emergent Evolution” in Proc. of Sixth Intern. Congress of Philosophy, at Cambridge, Mass., 1926 (published in 1927).