RELATIONSHIP OF SPECIES. 455 



between Boar and Sow is far less noticeable ; while the differ- 

 ence in other animals, such as Bull and Cow, Stallion and Mare, 

 is only readily discernible in the more concentrated effluvia of 

 their stables. 



I am, of course, aware of the oft-quoted characteristic 

 difference in the smell of the Caucasian and the Negro (which 

 are relatively distasteful to the senses of these races) who do 

 produce fertile offspring, and this may seem to contradict the 

 importance of any difference existing in this manner between 

 Horse and Ass, in so far as suggesting infertility, and thus being 

 of value as indicating increased variation. 



If we look further into this, however, it is possible this human 

 hybrid approaches perilously near the Horse and Ass mule, being 

 classed by Broca* as " paragenesic " (of low fertility); though 

 whether this latter view is correct or not is difficult to prove. 

 Anyhow, may not this difference in smell precede and not follow, 

 or arise with, the " agenesic " or entirely infertile stage? 



If it does precede this stage, then it does assist in producing 

 this stage, by causing distaste, and consequent segregation. 



Finally, the difference in smell in the two above examples 

 may not be connected with the same organs, and thus the 

 comparison is perhaps valueless. 



Further on in his article, after instancing the results quoted 

 above, and certain others obtained from birds, Mr. Finn asks : 

 " What is the reason of these discrepancies?" I cannot perceive 

 that in his instances there are any discrepancies, although, as it 

 is difficult to avoid being influenced by the general teachings of 

 our schemes of classification (which vary quite frequently, by the 

 way), these results may appear to be discrepancies. Judged by 

 congeneric actions the results seem very fairly regular, and I 

 should imagine that, when blood tests are better perfected, 

 these will again bear out these deductions. Mr. Finn himself 

 states further on in his paper that " we can say that the fertility 

 of a hybrid does depend to some extent, amongst birds, at any rate, 

 on the nearness of the species crossed." 



* ' On the Phenomena of Hybridity in the Genus Homo.' 



(To be continued.) 



