1886.] MR. J. B. SUTTON ON ATAVISM. 555 



prostate an luiimpeachable witness of an ancestry with the feathered 

 tribe, low down among the oviparous rejjtiles. 



Let me now proceed to show how very Httle information we possess 

 concerning latent germs which may be present in the embryo. For 

 example, the discovery of the germ of an os centrale in the carpus of 

 man was certainly startling. Yet its existence might have been 

 anticipated from what we know of the variations in the number of 

 the carpal ossicles in the adult. Atavism drew the attention of 

 anatomists to a secondary astragalus in the human tarsus, and Barde- 

 leben succeeded in detecting the germ. (This has been questioned by 

 Baur, but his objections are inconclusive.) We must now consider 

 some cases of a different character. 



Atavism in relation to Secondary Sexual characters. 



As Darwin points out ', two distinct elements are included under 

 the term "inheritance" — the transmission and the development of 

 characters. The distinction is a most important oue, especially in 

 its bearing on the question of Atavism, that the two conditions will be 

 illustrated b^' concrete examples. 



In most species of the Deer tribe it is the rule for the male alone 

 to possess antlers, vet it is a well attested circumstance that under 

 certain diseased conditions of the sexual organs, especially atrophy or 

 degeneration of the ovaries, rudimentary horns which are never shed 

 appear in the female. 



This shows us that although the female is in possession of the 

 secondary sexual organs in virtue of transmission, yet they remain 

 latent as a rule, and only become developed under extraordinary 

 circumstances. The same holds good for those cases of hens who 

 for years lay eggs, yet eventually cease to do so, put on one side the 

 plumage proper to their sex, and adopt more or less completely the 

 plumage of the cock. 



These examples open up the subject of secondary sexual charac- 

 ters. The question of primitive heraiaphroditism has been already 

 discussed in a preceding paper, and an attempt was made to show 

 that, for a brief period at least, the embryo presents sexual parts 

 common to the male and female, so that for a time it is absolutely 

 impossible to determine the sex. What is true of the embryo applies 

 equally to animals normally hermaphrodite : no distinctive charac- 

 ters are displayed externally. Also in cases of hermaphroditism 

 occurring in animals normally bisexual, the secondary sexual charac- 

 ters are intermediate to those of the fnnctional male and female. It 

 is therefore fairly evident that the female, though she differs from the 

 male in the non-development of secondary sexual characters, yet 

 possesses them in a latent condition ; or, to put the matter briefly, 

 they are transmitted, but not developed. 



This raises two questions, each of equal importance : — (1) How are 

 these characters transmitted? (2) What hinders tlieir develoi)ment? 



It seems to me that the second of these questions is the one with 

 which we are chiefly concerned here, and that the non- development of 

 ' ' Descent of Man,' 2nd ed. p. 227. 



