156 The Science of Life. 



to give up all belief in Darwin's theory of pangenesis. 

 After an examination of the evidence in support of the 

 Lamarckian postulate Galton summed up as follows : 

 "The inheritance of characters acquired during the 

 lifetime of the parents ' includes much questionable 

 evidence, usually difficult of verification. We might 

 almost reserve our belief that the structural cells can 

 react on the sexual elements at all, and we may be con- 

 fident that at the most they do so in a very faint degree 

 in other words, that acquired modifications are barely, 

 if at all, inherited in the correct sense of that word.' 



(1) In regard to climatic variations, Galton doubts 

 any reaction of the ' body ' upon the germs, but believes 

 that the germs are themselves directly affected. 



(2) The same is true in many constitutional diseases 

 that have been acquired by long-continued irregular 

 habits. 



(3) The cases of the apparent inheritance of mutila- 

 tions are outnumbered by the overpowering negative 

 evidence of their non-inheritance. 



(4) The case of Brown-S6quard's hereditarily epileptic 

 guinea-pigs, in consequence of an operation performed 

 upon the parents, is perhaps interpretable as the result 

 of imitative influence. 



(5) It is hard to find evidence of the power of the 

 personal structure to react upon sexual elements, that 

 is not open to serious objection. That which appears 

 the most trustworthy lies almost wholly in the direction 

 of nerve changes, as shown by the inherited habits of 

 tameness, pointing in dogs, and the results of Dr. Brown- 

 Sequard." 



Weismann, however, has the credit of having brought 

 the scepticism to a climax. He denied all inheritance 

 of acquired characters, finding no convincing evidence 

 that characters impressed upon the parental organism 

 by the surroundings, or acquired as the result of use 

 and disuse, can be transmitted. More than that, how- 

 ever, Weismann's whole theory of variation, adapta- 

 tion, and heredity raises, he believes, strong probabilities 

 against the inheritance of acquired characters. It is 

 necessary to quote a few of his sentences. 



