no AGRICULTURAL RESEARCH AND THE FARMER : 



according to the time of year ; that in winter it may be so short 

 (lasting only a few hours) as to be frequently overlooked in prac- 

 tice ; but that there are certain indications by which it is possible 

 for a farmer to ascertain approximately when a condition of 

 " heat " will arise, and by turning out the heifer with the bull 

 at that period he can practically ensure service. 



In these " heat " investigations, the observations on the 

 living animals are supplemented by and Unked up with a detailed 

 laboratory study of their breeding organs after death. Every- 

 thing possible is found out from close observation for some 

 weeks before the animals are killed, and afterwards such organs 

 as the ovaries, uterus, vagina, mammary glands, &c., are pre- 

 served and studied in detail. During the past year eleven 

 animals have been dealt with in this way, four of them being 

 pregnant. In order to detect with absolute accuracy the occur- 

 rence of the " heat " period, a bull is used which has been operated 

 upon in such a way that he can serve the cows but cannot make 

 them pregnant. X^lien pregnancy is desired recourse is had to 

 another bull. The work has lately been extended to cover a 

 comparative study of the development of the milk glands during 

 pregnancy,, for there is some reason for assuming that the milk 

 yield of an animal varies with the size of the milk tissue in the 

 udder. Four pregnant animals are being kept for the purpose of 

 this investigation and will be killed and examined at various stages 

 of pregnancy. Supplementary material is being obtained from 

 slaughterhouses. The aim of the investigation is to ascertain 

 what are the primary factors concerned in controlling the 

 formation of milk in the milk glands of the cow. Already a 

 considerable amount of work has been done with rabbits, and 

 certain definite conclusions drawn, which it is desired to confirm 

 or otherwise in the case of the cow. 



Another significant fact emerging from the work of this charac- 

 ter recently carried out has been the large wastage of what may 

 be called reproductive activity which occurs in the animals 

 examined. A study of the breeding organs of numerous sows, 

 rabbits and sheep has shown that the actual Htter is very much 

 smaller than the number of eggs originally fertilised. In rabbits, 

 out of an average of 20 eggs shed, only 12 developed normally 

 and gave rise to young animals; 4 or 5 degenerated, and the 

 remainder were missing. It is quite clear that abortion was not 

 due to bacteria, because the uterus in all cases was perfectly 

 clean and aseptic. Moreover, the condition was not found in 

 wild rabbits, so it seems that domestication has been responsible 

 for some derangement of the animal's internal functions, resulting 

 in a failure to give birth to the proper number of young. This 



