202 HEREDITARY CHARACTERS 



native in those organisms where the sexes are separated, but 

 in many ways it differs essentially. 



The production of both fertilising and fertilised gametes 

 by the same individual would appear to be a more primitive 

 condition than the production of only one kind of gamete 

 by each individual. The separation of the sexes, that is, the 

 alternative transmission of sex, necessitates our assuming 

 the pre-existence of an alternative mode of transmission 

 for some characters. Also we must remember that the 

 most perfect Mendelian results have been obtained from 

 organisms which are usually self-fertilised, in which sex 

 in the sense implied by the Mendelian experimenters does 

 not exist. It must be admitted then, by those who uphold 

 the purely Mendelian interpretation of the separation of 

 the sexes, that sex may sometimes be a Mendelian character 

 and sometimes may be blended. 



If secondary sexual characters are taken as being in- 

 cluded in sex, then the case becomes even more difficult, 

 for it is demonstrable in many cases that the secondary 

 sexual characters of both sexes are potentially present in 

 all individuals. 1 This would involve the supposition that 

 all individuals are impure dominants or impure reces- 

 sives (!), which would hardly be conceivable on Mendelian 

 lines. 



Archdall Reid proposes a theory exactly opposite to that 

 put forward by the Mendelians. He believes that " Men- 

 delian characters are non-sexual traits which are reproduced 

 in the sexual mode." " If we examine any of the so-called 

 Mendelian characters, we find that the majority may fairly 

 be described as secondary sexual characters, though not 

 necessarily as sexual differences, for example, colour and 

 form of plumage." " It seems clear, then, that there is no 

 real segregation, no real alternative inheritance, but only an 

 alternative production, alternative patency and latency." 2 



1 See p. 205. 



2 Reid, G. Archdall, Report of paper read to the Linneau Society, 

 December 19, 1907, Nature, January 9, 1908. 



