130 THE BREEDING OF ANIMALS 



extremity of the vulva. The mammary glands were 

 very small and but little developed and resembled more 

 the rudimentary mammary glands of a bull than the 

 normal glands of a cow. At two years of age this sup- 

 posed cow had never come in heat. She was permitted 

 to run in the same paddock with two mature bulls for a 

 period of six months, but never came in heat. This 

 animal was slaughtered and the reproductive organs 

 removed for examination. It was found that the animal 

 had a vulva and a very short vagina-like organ ending 

 in a blind sac. No uterus, Fallopian tubes or ovaries 

 were found. There was also found a rudimentary penis. 

 It seems probable that sterile free-martins are imperfect 

 males or hermaphrodites. It is not possible at this time 

 to give any satisfactory explanation of why there should 

 exist a greater tendency to hermaphroditism when twins 

 of different sex are born than twins of identical sex. It 

 is still more difficult to explain why this phenomenon 

 should occur exclusively among cattle. It is possible 

 that the explanation of this phenomenon is associated in 

 some way with the production of identical twins, but 

 this does not offer any satisfactory explanation of why 

 this strange occurrence should be found in the bovine 

 species alone. 



