14 HERBERT SPENCER AND 



in the germ ; for if it did not, the facts of heredity could 

 not be accounted for, and in his theory of pangenesis 

 supposed that every cell in the body gave off minute 

 gemmules, which, passing into the circulation, were 

 stored in the germ-cells. 



Sir Francis Galton experimentally disproved the theory 

 of gemmules, and propounded a theory of ' stirps ' to 

 account for the phenomena of heredity. Into the details 

 of this theory it is not now necessary to enter. It 

 attracted little attention in this country and passed 

 unnoticed on the Continent and in America ; but it was, 

 in fact, an anticipation of the principles underlying 

 Weismann's more celebrated theory of the germ-plasm. 



It is not my intention to attempt to give you an account 

 of Weismann's theory, and it would be impossible to do 

 so in the time at my disposal. It was explained by its 

 author in the Romanes Lecture in 1894, and has since 

 undergone some alteration, to harmonize it with the 

 rapidly accumulating evidence on the numerous aspects 

 of development and heredity — this evidence being the 

 result of researches largely stimulated by the theory itself. 

 The main features, however, remain unaltered, and I need 

 only mention such of them as are directly relevant to 

 Herbert Spencer's arguments. 



In the first place, Wei smann. by a rarf^f^l f;riti^i'^Tn 

 of a large number of supp o^^pd ^p<;pt;, rpjprfpd nnf^ of the 

 main suppor ts of Spencer's system. He showed that not 

 only ^ ther e no evidence that characters acquired dur- 

 ing th e, lifetime of an organism are transmitted t o its 

 des cendants, but the evi dence points strongly to the fact 

 th at_such acquired characters are not and cann ot be 

 franqmittgd by inherita nce. 



If this is accepted as an established fact (as it is by most 

 naturalists in this country, but not in America) it follows 

 that the secu lar increase of complexity of organiz ation 

 demanded by the theory of Evolution cannot have b een 

 produce3^ directly by the action of incident forces as 



