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work of Mendel, Bateson, De Vries, and other experimentalists, and 
look at the difficulties which Driesch, and more lately Bergson, have 
found in the acceptance of the usual theories of descent. Driesch 
emphasises the fact (well known to biologists) that Natural Selec- 
tion is not a creative factor. It does not explain the existence of 
certain animal and vegetable forms except by stating that all forms 
which do not exist are absent because they cannot exist or have never 
been produced. In the words of Driesch : — “Do we understand in the 
least why there are white bears in the Polar regions if we are told 
that bears of other colours could not survive.” There is nothing in 
these statements, of course, which is contrary to the writings of Dar- 
win. The point is merely emphasised that the Variations on which 
Darwin assumed Natural Selection to act are taken for granted. In 
other words no satisfactory explanation is forthcoming for the first 
appearance of Variations— the really fundamental phenomena of 
Evolution. 
In addition, Driesch makes the criticisms that Darwinism can- 
not explain “the mutual adaptions between plants and insects; that 
it can never account for the origin of those properties that are in- 
different to the life of their bearer; that it fails in the face of all 
portions of organisms which are composed of many different parts 
— like the eye — and nevertheless are functional units in any passive 
or active way; and that, last not least, it has been found to be quite 
inadequate to explain the first origin of all newly formed constitu- 
ents of organisms even if they are not indifferent : for how could 
any rudiment of an organ which is not functioning at all, not only 
be useful to its bearer, but be useful in such a degree as to decide 
about life or death” ? 
The assumption that acquired characters could be inherited 
would, it is true, simplify, indeed it might explain, many of the above 
problems, and I see no reason yet for believing that acquired char- 
acters are not inherited. It would not explain all. 
What does Driesch suggest as a solution of the problem 1 ? He 
considers that the non-material factor to which we have already been 
introduced, viz., Entelechy, is at the root of all transformism of 
species. 
Bergson has evidently felt the same difficulties as Driesch and in 
his inimitable manner has devoted some time to an expression of the 
obstacles in the way of an acceptance of an accidental occurrence 
of co-ordinated variations. As one of the chief examples dealt with 
by Bergson is a structure on which I have spent some little time in 
research , 1 I feel no apology is needed for discussing the case here. 
The example comes from the well-known mollusc Pecten (the com- 
mon Scallop), species of which exist all over the world. This animal, 
although in many details of organisation not very highly developed, 
1 Dakin. The Eye of Pecten. Q.J.M.S. Vol. 55. 1910. 
