THE LAMARCKIAN PRINCIPLE 45 



reproductive cells. 1 The machinery required is very elaborate. 

 Darwin, as I have already mentioned, formulated a provisional 

 theory to which he gave the name of Pangenesis, according to 

 which every part of the body gave off gemmules or very small 

 particles and these somehow found their way to the cells from 

 which succeeding generations were to spring. Every other 

 theory suggested is but a modification of this and must stand or 

 fall with it. There have been found, it is well to own, thin 

 threads of protoplasm which are not parts of the cells but which 

 pass among them and it has been held that these threads are 

 channels of communication. I scarcely think that their existence 

 simplifies the problem. It must be remembered that these 

 countless gemmules from all parts of the body have not only 

 to be conveyed to the reproductive cells and to find their way, 

 some of each kind, into each of them ; in addition to this, when 

 they have obtained admittance, we are asked to believe that, the 

 cells do not, like all other living creatures and like themselves 

 when they absorb other living material, treat what they take in 

 as food and assimilate it. On the contrary, the gemmules, 

 according to the theory, maintain their character and yet 

 another miracle each finds its place in the complicated archi- 

 tecture of the cell. And how does this affect the question 

 of heredity ? This small cell must carry the characteristics of 

 the race. If no additions are made to it except in the way of 

 nourishment which it assimilates, we can imagine, difficult 

 though it may be, that thousands of characteristics are packed, 

 each in its place, within that tiny envelope. But if hosts of new 

 gemmules, each the bearer of some new quality, are constantly 

 knocking and finding admittance, what is to become of the old 

 inhabitants, the gemmules in whose safe keeping are the dis- 

 tinctive features of the race ? It is difficult even for the 

 imagination to work out the theory of Pangenesis or any 

 similar theory. 



1 It has been pointed out by Mr Adam Sedgwick that, though the two arms 



are correlated with one another, yet one may be greatly developed by exercise 



without the other sharing appreciably in the development. How then should the 

 reproductive cells be affected ? 



