20 peesident's address. 



Even if we allow Weismanu's method of providing for the identity 

 between the germ-cell of two successive generations, there remains, as 

 above indicated, a greater problem — namely, that of ontogeny. We no 

 longer look at the potentiality of a germ-cell as Caliban looked on Setebos, 

 a.s something essentially incomprehensible ruling the future in an un- 

 known way — ' just choosing so.' If the modern germ-cell is to have 

 a poetic analogue it must be compared to a Pandora's box of architectonic 

 sprites which are let loose in definite order, each serving as a master 

 builder for a prescribed stage of ontogeny. Weismann's view of the 

 mechanism by which his determinants — the architectonic sprites — come 

 into action in due order is, I assume, satisfactory to many, but I confess 

 that I find it difficult to grasp. The orderly distribution of determinants 

 de23ends primarily on their arrangement in the ids, where they are held 

 together by ' vital affinities.' They are guided to the cells on which they 

 are to act by difterential divisions, in each of which the determinants are 

 sorted into two unequal lots. They then become active, i.e., break up into 

 biophores, partly under the influence of liberating stimuli and partly by 

 an automatic process. Finally the biophores communicate a ' definite 

 vital force ' to the appropriate cells.' This ma^/ be a description of what 

 happens ; but inasmuch as it fails to connect the process of ontogeny 

 with physiological processes of which we have definite knowledge, it does 

 not to me seem a convincing explanation. 



For myself I can only say that I am not satisfied with Weismann's 

 theory of heredity or of ontogeny. As regards the first, I incline to deny 

 the distinction between germ and soma, to insist on the plain facts that 

 the soma is continuous with the germ-cell, and that the somatic cells 

 may have the same I'eproductive qualities as the germ-cells (as is proved 

 by the facts of regeneration) ; that, in fact, the germ-cell is merely a 

 specialised somatic cell and has the essential qualities of the soma. With 

 I'egard to ontogeny, T have already pointed out that Weismann does not 

 seem to explain its automatic character. 



The Mnemic Theory. 



If the mnemic theory is compared with Weismann's views it is 

 clear that it is strong precisely where these are weakest — namely, in 

 giving a coherent theory of the rhythm of development. It also bears 

 comparison with all theories in which the conception of determinants 

 occurs. Why should we make elaborate theories of hypothetical deter- 

 minants to account for the potentialities lying hidden in the germ-cell, 

 and neglect the only determinants of whose existence we have positive 

 knowledge (though we do not know their precise nature) ? We know 

 positively that by making a dog sit up and then giving him a biscuit we 

 build up something in his brain in consequence of which a biscuit becomes 

 the stimulus to the act of sitting. The mnemic theory .assumes that the 



' The Erohitiiiri Tltrari/, Eng. trans., i. .37:? el st'/j. 



