Darzi'lns Pangenesis 65 



gifted investigator, partly also to the circumstance, al- 

 ready mentioned, that Darwin himself represents the first 

 proposition as a matter of course and generally known, 

 and presents only the second one as his own hypothesis.^" 



The assumption of the transportation of gemmules, 

 which was, especially for plants, very greatly limited by 

 Darwin himself, has been denied so frequently, and with 

 so much ingenuity that it would be superfluous to criticise 

 it any further here. Especially to Weismann is the credit 

 due of showing how little it is demanded by well known 

 facts and tested experience. The cases collected by Dar- 

 win, which seemed to require it,^^ were exceptions, and 

 their trustworthiness has been strongly shaken by Weis- 

 mann.^^ I believe I need only cite here the works of this 

 investigator.^^ 



Freed from the hypothesis of the transmission of 

 gemmules, pangenesis now appears to us in the purest 

 form. It is the assumption of special material bearers 

 for the various hereditary characters. It is true that 

 Darwin does not always express himself clearly as to 

 what he calls one hereditary character, and occasionally 



32ln his letters also, he lays the greatest stress on this part. Cf. 

 Life and Letters of Charles Danvin. 3: 72-120. (2: 264. New York. 

 1901.) 



33The well-known experiments of Brown-Sequard, which are so 

 frequently quoted as supporting the theory of the heredity of ac- 

 quired characters, were regarded by Darwin himself as opposing his 

 hypothesis of the transportation of gemmules. Cf. Darwin. The 

 Variation of Animals and Plants. 2: 392. 



^^Weismann, A. Ueber die Vererbung. 1883 ; also Die Bedeutung 

 der sexuellen Fortpflansung fUr die Selektionstheorie. p. 93, etc. 1886. 



s^The so-called graft-hybrids, and the remarks on the influence 

 of the male element on the parts surrounding the germ, give no proof, 

 to my mind, of the necessity of an assumption of transmission. Cf. 

 Part II, D, 5, p. 207. 



