134: - PRINCIPLES OF STOCK-BREEDING. 



Among cattle, where twin calves are produced, 

 the one a male and the other a female, the latter, 

 called a free-martin, is, as a rule, barren. When the 

 twins are of the same sex, the reproductive powers 

 are not impaired. 



In all other varieties of animals, so far as known, 

 when males and females are born together as twins, 

 the females are as prolific as if born singly. In free- 

 martins the internal generative organs are generally 

 imperfect, partaking of the characters of both male 

 and female organs. In appearance these imperfect 

 females frequently resemble steers, the feminine char- 

 acteristics being mostly wanting. 1 



In rare instances the free-martin is capable of 

 breeding, the reproductive organs not having become 

 malformed from her intra-uterine development with a 

 male. 



Youatt, in his work on " Cattle," gives but two 

 cases of fertile free-martins. Dr. Hunter dissected a 

 free-martin calf, that died when a month old, and 

 found the sexual organs naturally constituted, and he 

 also heard of two instances in Scotland of free-martins 

 that were prolific. 



Dr. Maulson has likewise published similar cases 

 in London's Magazine of Natural History? 



A few additional cases might be gathered from 

 the agricultural papers, but they only serve to show 

 that fertility under such conditions is decidedly ex- 

 ceptional. 



1 " Cyclopaedia of Anatomy and Physiology," vol. ii., pp. 701, 702, 

 735, 736. Youatt on " Cattle," p. 638. 



8 " Cyclopaedia of Anatomy and Physiology," vol. ii., p. 735. 



