THEORY OF GENERATION 163 



the uterus first, it will still cause a fruitful impregnation, because it 

 remains there (or in the fallopian tubes) uninjured until the descent of 

 the ovum. 



11. The Influence op the Male upon the embryo is partly dependent 

 upon the fact, that he furnishes a portion of its substance in the shape of 

 the sperm-cell, but also in great measure upon the effect exerted upon the 

 nervous system of the mother by him. Hence, the preponderance of one 

 or other of the parents will, in great measure, depend upon the greater or 

 less strength of nervous system in each. No general law is known by 

 which this can be measured, nor is anything known of the laws which 

 regulate the temperament, bodily or mental power, colour or conformation 

 of the resulting offspring. 



12. Acquired Qualities are transmitted, whether they belong to the 

 sire or dam, and also both bodily and mental. As bad qualities are quite 

 as easily transmitted as good ones, if not more so, it is necessary to take 

 care that in selecting a male to improve the stock he is free from bad 

 points, as well as furnished with good ones. It is known by experience 

 that the good or bad points of the progenitors of the sire or dam are almost 

 as likely to appear again in the offspring as those of the immediate parents 

 in whom they are dormant. Hence, in breeding, the rule is, that like 

 produces like, or the likeness of some ancestor. 



13. The purer or less mixed the breed the more likely it is to be 

 transmitted unaltered to the offspring. Hence, whichever parent is of the 

 purest blood will be generally more represented in the offspring ; but as 

 the male is usually more carefully selected and of purer blood than the 

 female, it generally follows that he exerts more influence than she does ; 

 the reverse being the case when she is of more unmixed blood than the sire. 



14. Breeding "In-and-in" is injurious to mankind, and has always 

 been forbidden by the Divine law, as well as by most human lawgivers. 

 On the other hand, it prevails extensively in a state of nature with all 

 gregarious animals (such as the horse), among whom the strongest male 

 retains his daughters and grand-daughters until deprived of his harem by 

 younger and stronger rivals. Hence, in those of our domestic animals 

 which are naturally gregarious, it is reasonable to conclude that breeding 

 " in-and-in " is not prejudicial, because it is in conformity with their 

 natural instincts, if not carried farther by art than nature teaches by 

 her example. Now, in nature, we find about two consecutive crosses of 

 the same blood is the usual extent to which it is carried, as the life of 

 the animal is the limit ; and it is a remarkable fact that, in pi'actice, 

 a conclusion has been arrived at which exactly coincides with these 

 natural laws. " Once in and once out " is the rule for breeding given by 

 Mr. Smith in his work on the breeding for the turf; but twice in will 

 be found to be more in accordance with the practice of our most successful 

 (early) breeders. 



15. The influence of the first impregnation seems to extend to the 

 subsequent ones ; this has been proved by several experiments, and is 

 especially marked in the equine genus. In the series of examples pre- 

 served in the museum of the College of Surgeons, the markings of the 

 male quagga, when united with the ordinary mare, are continued clearly 

 for thi'ee generations beyond the one in which the quagga was the actual 



