THE AMERICAN TROTTING HORSE. G23 



equally unfounded. Mares are often bred to horses after having 

 been bred to ^n ass, and nobody ever sees a foal by a horse from 

 guch a mare look like a mule. I have known several instances of 

 white women having mulatto children, and afterwards having 

 children by white men ; and in no instance was the influence of 

 the negro perceptible on the child of the Caucasian father. If 

 any man has a good mare that has produced a colt from a scrub 

 stallion, he need not hesitate, on that account, to breed her to a 

 good horse, if he has an opportunity. 



Breeders often dpsire that a colt shall be a male, or a female ; 

 but that is always left to chance for the best of reasons. It ia 

 probably possible, however, to discover the laws governing the 

 production of sex, and also possible to so control their action as to 

 attain the desired result. Some chance experiments in breeding 

 dogs, so long ago as 1845, induced me to a more careful investiga- 

 tion of the subject. I discovered, that if a slut were kept until 

 near the last of her heat, before a dog was admitted to her, the 

 pups would be chiefly males ; but if she were at large, with all 

 the dogs of the neighborhood, from the beginning of the heat, 

 they would be mostly females. Further experiments, and on 

 other species of animals, were prevented by removal to a city ; but 

 having called public attention to the matter, in lectures on physi- 

 ology in several states, others have pursued the investigation with 

 very satisfactory results. Dog-breeders make practical application 

 of the discovery in hundreds of instances, and a few dairy-men 

 have found it applicable to cows. The theory is, that if the female 

 is long in heat before conception, it implies a scarcity of males, 

 and Nature supplies the deficiency by producing them. I also 

 noticed that if a cock had many hens, the chicks would be mostly 

 males. This I had but one opportunity of observing. The single 

 observation, however, is in conformity with the same law. Apply- 

 ing the law to horses, it would follow that, other things being 

 equal, the more mares he served in one season, the more of his 

 colts would be males. The action of the law would be modified 

 by the time of the mare's heat when put to him, and by the cir- 

 cumstance that his sire, his grandsire, and so on, for many genera- 

 tions, had been used to serving many mares in one season — so that 

 the power to do so without forcing the action of the law would 

 have become hereditary. If the mare were served in the begin- 

 oing of her heat, we might expect a mare foal ; and if in the last 

 part of the erotic season we might, by the same rule, expect a 

 horse foal. Of course, the conditions mentioned as affecting the 

 stallion might modify the result. If a mare were put to a horse 

 in the last part of her heat, and if the horse had quite recently 

 served one or more other mares, the conditions would be favorable 

 on both sides to the production of a male offspring. If the case 



