88 STRUCTUEE AND ECONOMY OF THE HORSE. 



blood, contrary to the usual custom. The blood from the um- 

 bilical veins, as well as the lower part of the body, enters both 

 sides of the heart at once, and a small portion is thence sent into 

 the lungs from the right ventricle, whilst the largest portion 

 is distributed to the system from the left ventricle. 



There is a communication, too, between the aorta and the 

 pulmonary artery, by which the blood not required by the lungs 

 is sent into the system through the aorta. It will thus be seen 

 that the heart of the foetus, though double in its construction, is 

 single in its office ; and, in this respect, is very analogous to the 

 single heart of some cold-blooded animals. No sooner, however, 

 does the animal breathe, than the right side of the heart has an 

 independent office to perform, and the communications before 

 spoken of are closed up. — Ed.] 



CHAP. XX. 



ON THE PRINCIPLES AND PRACTICE OF BREEDING. 



[The comparative influence of the male and female in the 

 formation of the offspring has been the subject of much dispute 

 amongst physiologists, and is a matter on which there is still 

 much diffei'ence of opinion. Some contend, that the influence 

 of the male is every thing, and that the female only affi^)rds the 

 soil for the nourishment of the foetus. Others argue, that the 

 seed is afforded by the female, who has therefore the greatest 

 influence over the future offspring, and that the male only ex- 

 cites this seed into the action necessary for the production of 

 the young animal. The question, however, is not to be de- 

 cided by anatomy, or physiology, but only by the evidence of a 

 number of practical results. The germ of the future oftspring 

 is certainly supplied by the female ; but still the form and 

 qualities may be the effect of the male, just as the ductile wax 

 receives whatever impression the stamp may be calculated to 

 produce, whether the head of a prince or that of a peasant. We 

 must therefore look only to facts, to decide the point. It is a 

 matter of some importance in the breeding of animals to have 

 as correct views as possible on this subject, for it is too fre- 

 quently the case that either one parent or the other is entirely 

 disregarded in the choice, and the result is a weakly, mongrel, 

 or bad-shaped animal. In crossing the breed of animals, I think 

 it will be found that the offspring turns mostly after the sire 

 both in shape and in size. The common mule begotten by the 

 male ass out of the mare certainly discovers a much stronger 

 affinity in shape and size, and in disposition too, to his plebeian 



