TWINNING IN RUMINANTS 109 



This condition seems to me barely possible, but very 

 improbable. 



Twinning in the genus Dasypus and twinning in 

 ruminants turn out to be two totally different phenom- 

 ena. In Dasypus, the twins are monozygotic and 

 always of the same sex. In cattle, twins are dizygotic 



Fig. 40. — Photograph of triplet calves (from Pearl) 



and may or may not be of the same sex. The additional 

 phenomenon of freemartinism adds materially to the 

 value of bovine twins, especially in its bearings on the 

 problems of sex-biology. In a subsequent chapter 

 some of these bearings receive a more adequate dis- 

 cussion in connection with other sex-phenomena in 

 twins than is possible at this time. 



