GrEOFFREY BmITH AND MrS HaIG ThOJIAS 49 



transference ; in Crustacea on the other hand the converse is true, viz. 

 that assumption of female characters by the male is generally associated 

 with abnormality of the gonad, while the assumption of male characters 

 by the female is unaccompanied by abnormality of the gonad. 



This might be taken to indicate that in Birds the female carries 

 the male primary se.xual quality in a latent state which on the removal 

 or abnormality of the ovary comes into activity and stimulates the 

 developement of the male secondary sexual characters, while in 

 Crustacea the male carries the female primary sexual quality which on 

 removal or abnormality of the testis or owing to the activity of some 

 special stimulus comes into activity and stimulates the developement 

 of the female secondary sexual characters. 



Although it would be rash to press this argument, the apparent 

 difference in the reaction of the sexes in Crustacea and Birds would 

 seem to argue a different physiological constitution in respect to the 

 distribution of the primary sexual character to the two sexes. In 

 regard to the distribution of the secondary sexual characters to the 

 two sexes, it appears probable that each sex is carrying the opposite 

 secondary sexual characters in a latent state. This is most clearly 

 proved by Mrs Haig Thomas' hybridising experiments with pheasants 

 where she has been able to prove that the female can transmit to her 

 male offspring the male secondary sexual characters of her species, and 

 also that the male can transmit to his female offspring the female 

 secondary sexual characters of his species. This fact is well illustrated 

 by the hybrid pheasants dealt with in this paper. The detailed 

 evidence, however, cannot be given here but will be described in 

 a separate paper by Mrs Haig Thomas. 



3. The secc-ratiu of hi/brid pheasants. 



In an interesting paper Guyer (2) has called attention to the 

 preponderance of males over females produced by crossing different 

 varieties among Gallinaceous and other birds. In Part 9 of my 

 studies (3) I alluded to this observation and recorded that as far as my 

 experience went the same preponderance was met with. The following 

 statistics which Mrs Haig Thomas has derived from her extensive 

 experiments in raising hybrid pheasants are of exceptional value, 

 because the sexes of the birds were determined in doubtful cases by 

 dissection, and also a record was kept of the number of infertile eggs, 

 of the number that died in the shell, and in certain cases the sex of the 

 birds that died in the shell was determined. They also include a very 



Joum. of Gen. iii 4 



