

SEXUAL AND MENDELIAN TRAITS 191 



separation subsequently. 1 In like manner, when varieties are 

 crossed, a pseudo-hermaphroditism is not uncommon, that is, the 

 inheritance of male and female characters is then particulate, the 

 separation into male and female sets is not preserved ; there is on 

 the contrary Mendelian independence of characters. (/) As we 

 have seen, there is no real segregation of Mendelian any more 

 than of sexual characters. There is only patency and latency. 

 (k) Sometimes both alternative Mendelian characters, for example, 

 extra toe and normal foot in poultry, appear, like the sexual 

 characters, in the different individuals of the first hybrid genera- 

 tion, and would continue to appear in each succeeding generation 

 were they like the sexual characters crossed in each generation. 

 (/) In other instances, the Mendelian traits are long latent, like the 

 sexual characters in aphides ; but like them reappear at length, as 

 in cases of reversion in pure-bred varieties. 2 (m) In another pecu- 

 liarity, and that a very striking and important one, Mendelian 

 and sexual characters display a suggestive resemblance. Both 

 are traits in which, unlike fluctuations, the mating individuals are 

 strongly contrasted ; for the Mendelian characters are usually 

 mutations or characters which originated by mutation in ancestors. 



315. Plainly, the parallel between sexual and Mendelian 

 reproduction is very close. It is so close that experimental 

 workers, though they have not by any means perceived all the 

 likenesses, have surmised that the inheritance of sexual characters 

 accords, in many instances at least, with Mendel's laws. 3 Indeed, 

 they have supposed that the inheritance of sex is merely an 

 example of Mendelian inheritance, 4 and that continued investi- 

 gation will eliminate any apparent contradictions and anomalies. 

 But another interpretation of the facts is conceivable. Examine any 

 list of Mendelian characters, for example those of poultry 5 or peas.* A 

 glance shows that, as a rule, the majority of the items in such a list are 

 sexual in the sense that, as attractions or otherwise, they are concerned 

 with reproduction. It is possible, then, that, so far from it being 

 a fact that the reproduction of sexual characters is an example of 

 reproduction of Mendelian characters, the reverse may be the case. 



316. The question we are now in a position to ask ourselves 

 is, Which mode of reproduction, the sexual or the Mendelian, 

 contains the other ? Which is a variety of the other ? In deciding 



1 Inheritance in Poultry, p. 85. 2 See 280. 



3 See Bateson, Mendel's Laws of Heredity, chapter x. 



4 See Castle, Heredity oj Sex. 



5 See 288. 6 See 257. 



