84 A TREATISE ON HORSE-BREEDING. 



9th. In uniparous animals every successive ovum that 

 reaches maturation is of the opposite sex from that which 

 immediately preceded it. Hence, by serving 1 on the second 

 occurrence of heat we may secure the same sex as in the last 

 foetus. 



10th. The stage of development attained by the ovum at 

 the period of impregnation determines the sex of the product 

 of fecundation, the less developed proving females, the more 

 mature males. 



llth. The personal preponderance in strength and vigor 

 of the one parent will determine an excess of its own sex in 

 the progeny. 



12th. The nature of the food of the parents, and particu- 

 larly of the mother before conception, will influence the pro- 

 duction of the different sexes. 



The theory that just now appears to be more 

 generally believed in than any other is the 9th 

 in the foregoing list. This in based upon the 

 belief that, naturally, animals which usually 

 bring forth but one at a birth will produce the 

 sexes alternately that if the first ovum pro- 

 duces a male, the next ovum, if impregnated, 

 will produce a female; consequently, if a cow 

 or a mare, after having produced a female, is 

 impregnated at the first period of heat there- 

 after, the produce will be a male. If female 

 produce only is desired, one period of heat 

 should elapse after the birth of a female be- 

 fore the dam is again served by the nlale. This 

 is what is known as the Stuyvesant theory, 

 and many cattle-breeders of my acquaintance 

 firmly believe that it can be relied upon in a 

 majority of cases. 



