I08 WILD TRAITS IN TAME ANIMALS. 



there were some material distinctions in the 

 special outward circumstances which created the 

 need for such things in these animals. One 

 clue to the mystery, therefore, may be found by 

 studying how the habits and history of wild 

 asses and zebras differ from those of the wild 

 horse. 



Now here is a subject upon which some enter- 

 prising young naturalist may exercise his wits 

 and his capacity for original research. If any 

 one succeeds in solving the problem, he will 

 certainly receive one reward for Avhich many 

 men of science have been content to labour ; for 

 his name will be quoted as an authority, and 

 will pass down to future generations in every 

 book which may be written upon the natural 

 history of the Equidae.^ 



1 Dr Bonavia, in his ' Studies in the Evolution of Animals,' has 

 put forward the view that the callosities may be remnants of 

 glandular structures secreting an odoriferous material which was 

 useful in enabling horses to find one another after they had be- 

 come scattered. One piece of evidence, however, which would 

 have done more than anything else to prove or disprove this 

 hypothesis he has omitted. If the callosities in a newly-born 

 or fcEtal foal were found, when examined microscopically, to 

 contain tissue similar to that of ordinary odoriferous glands, 

 the problem would, I think, have been wellnigh solved. Until 

 this has been done the question must still remain an open one. 



