SEX-CHARACTERS IN EVOLUTION 121 



from the testis should be regarded as In any sense 

 the origin of the antlers of a stag. If so, why should 

 not antlers equally develop in the stallion or in the 

 buck rabbit, or indeed in man ? How far Doncaster 

 is right in holding that the soma is different in the 

 two sexes is a question already mentioned, but it is 

 obvious that in each individual the somatic sexual 

 characters proper to its species are present potentially 

 in its constitution by heredity — in other words, as 

 factors or determinants in the chromosomes of the 

 zygote from which it was developed ; but the normal 

 development of such characters in the individual 

 soma is either entirely dependent on the stimulus 

 of the hormone of the gonad or is profoundly in- 

 fluenced by the presence or absence of that stimulus. 

 The evidence, as we have seen, proves that, at any 

 rate in the large number of cases where this relation 

 between somatic sex-characters and hormones pro- 

 duced by the reproductive organs exists, the char- 

 acters are inherited by both sexes. In one sex they 

 are fully developed, in the other rudimentary or 

 wanting. But the sex, usually the female, in which 

 they are rudimentary or wanting is capable of trans- 

 mitting them to offspring, and also is capable of 

 developing them more or less completely when the 

 ovaries are removed, atrophied or diseased. If 

 we state these facts in the terms of our present 

 conceptions of chromosomes and determinants or 

 factors, we must say that the factors for these 

 characters are present in the chromosomes of both 

 male and female gametes. The question then is, 

 how did these factors arise ? If they were muta- 

 tions not caused by any influence from the exterior, 

 what is the reason why these particular characters 



