REGENERATION 1 3 9 



As has just been shown, it is also possible to make the reverse 

 hypothesis, and to suppose that although the whole of the idio- 

 plasm is contained in each cell, only that particular primary 

 constituent which properly concerns the individual cell has any 

 effect upon it. The activity of a primary constituent would thus 

 depend not on the idioplasm of the cell, but on the influences aris- 

 ing from all the cells of the organism as a whole. We should 

 thus have to suppose that each region of the body is controlled 

 by all the other regions, and should therefore practically be 

 brought back to Spencer's conception of the organism as a 

 complex crystal. This simply means giving up the attempt to 

 explain the problem at all, for we cannot form any conception 

 of such a controlling influence exerted by the whole on the 

 millions of different parts of which it consists, nor can we bring 

 forward any analogy to support such a view, the acceptance of 

 which would render a great number of observations on the 

 phenomena of heredity totally incomprehensible. What ex- 

 planation, for instance, could be given of the fact that a certain 

 human birthmark is always inherited on the left side only ? 

 According to this hypothesis, the germ-plasm contained in the 

 cells of this region w-ould be present on the right side just as 

 much as on the left : as the two halves of the body are alike 

 in other respects, we cannot suppose that the whole aggregate 

 exerts different influences as regards this region on the left and 

 on the right sides. 



It seems to me. therefore, that we must not give up the hy- 

 pothesis of the self-determination of the cells, in spite of its 

 apparent refutation by the facts described by Chabry and 

 Driesch. Moreover, I think these facts can be explained — in 

 principle at any rate — in another manner, viz., by attributing the 

 processes observed to regeneration, the arrangement for wliicli, 

 however, has not been provided for the first stages of segmenta- 

 tion, but for a later period of ontogeny. 



It is hardly to be expected that the first stages of segmenta- 

 tion should be in a sense purposely arranged for regenera- 

 tion. Both in Ascidians and sea-urchins the number of eggs 

 produced is so large, that it probably matters very little whether 

 a segmenting ovum perishes or becomes regenerated when one 

 half of it has been eaten by a small enemy. I do not, however, 

 wish to do away entirely with the idea that the eggs of certain 

 animals may conceivably be protected in this manner from 



