Fig. 17.
This demonstration is very important, so let us make it as clear as possible: Driesch’s logical proof of vitalism may be stated as follows:—
The different parts of the blastula are going to become different parts of an embryo.
The part a, occupying a definite position in the entire blastula, is going to become a definite part, having a definite position, in the embryo;
But each partial blastula becomes an entire embryo and the same part a occupies a different position in each.
Therefore any part of the blastula may become any part of the embryo.
Now if a mechanism is involved, it must, according to our ideas of mechanism, be one which is different in its parts, for each part of it produces a different result from the others;
But since any part of the mechanism may produce any of the different results contained in the embryo, every one of its parts must be similar to every other one.