TRANSMISSION OF CHARACTER 201 



with bacteria, although we find no trace of it in the 

 adult organisms. 



Such restrictions and reservations can only obscure 

 and complicate the discussion of the cases cited in sup- 

 port of the transmission theory. Every time the 

 transmission of an acquired character has been dem- 

 onstrated, the systematic opponents of the transmis- 

 sion theory have declared that this character was not 

 truly an acquired character. The only cases they ac- 

 cept as evidence are those in which the transmission 

 of a character cannot be proved and in which the char- 

 acter might be considered as innate. And it is prob- 

 ably the difficulty encountered in finding cases which 

 fulfil all the requirements, which is responsible for the 

 strange fact that instead of presenting numberless 

 examples, as we should expect if their contention were 

 true, the Lamarckians present very few of them in 

 support of their thesis, and always the same ones at 

 that. 



Both the Neo-Darwinians and the Neo-Lamarck- 

 ians instance cases which can be accounted for by their 

 respective theories. What complicates the discussion, 

 however, and makes proof hard to furnish, is that each 

 party demands that the other bring negative proof: 

 the Neo-Lamarckians must prove that a certain mod- 

 ification cannot be due to natural selection; the Neo- 

 Darwinians must prove on the contrary that it cannot 

 be due to the hereditary transmission of acquired char- 



