SEARCH FOR BARREN COWS. 49 



no less than eight to twenty follicles in various stages of development are to be found 

 in an ovary the chance of a female ultimately leaving the rookery unimpregnated is 

 very small. It is evident also from the actions of the old bulls, a certain percentage 

 of whom return in September to their places on the breeding grounds after feeding, 

 that should any cow fail to be served in June, July, or August she would find service 

 even in September. Microscopic examinations made by Dr. J. J. Carroll put this 

 beyond doubt. Sections made from the testes of a bull killed August 26, which had 

 recently withdrawn from tlie rookery, contained no spermatozoa, while sections made 

 from a bull killed October 17, contained spermatozoa in great numbers. In the old 

 bulls the testes are more or less withdrawn from the scrotum at the close of the breed- 

 ing season, simultaneously with the withdrawal of the bull from the rookery, and his 

 demeanor is completely changed. From being alert and aggressive he becomes quiet 

 and timid. Instead of perpetually quarreling with bis neighbors, bullying the bache- 

 lors and savagely resenting the intrusion of man, he lies down to sleep witb seals of 

 all ages, and flees precipitately from the sight or smell of a man. 



That sucli belated service sometimes occurs is borne out by tlie fact that several 

 hundred small black pups were noted in October on tbe rookeries of St. Paul. One 

 of these, killed on October 18, was found in good condition and with stomacb full of 

 milk. It weighed 11^ pounds. An unborn fetus, taken from a cow on Zapadni Eeef 

 August 14, weighed 11 pounds, and tbe experimental pup, taken from Tolstoi rookery 

 on August 1, supposed to be about a month old, weighed 12 pounds. A gray pup, 

 killed at the same time as the small black one, weighed 29 pounds, and two weeks 

 before a similar pup had been killed on the same rookery which weighed 33§ pounds. 

 The little pup could not have been much over a month old, and therefore must have 

 been born in September. 



As a result of the examination of 146 ovaries of adult cows it can safely be said 

 that there is nothing whatever to corroborate Br. Slunin's statement that it is possible 

 to determine from the appearance of the ovaries how many young have been borne by 

 a cow. In no case were two scars present on an ovary, to say nothing of there being 

 a greater number, and while in a single instance there seemed to be two scars on one 

 ovary a section showed that the appearance was merely superficial and not due to the 

 rupture of an ovvim. The scar of impregnation, cori^us luteum, develops very slowly 

 and slowly disappears, a cross section of the ovary revealing its presence long after 

 all traces have disappeared from the surface. Dr. Slunin, it is stated, examined the 

 ovaries in alcohol, and he probably mistook the slight depressions caused by the 

 shrinkage of the Graafian follicles for scars. A section of the nonfunctional ovary 

 shows it to be a fine grained, homogeneous mass with no developing follicle, while 

 the ovary which is for the season functional may have as many as eight Graafian 

 follicles in various stages of development. 



Careful search was made for "barren cows;" 3 females found with the bachelors 

 were killed for examination, and the ovaries of all females taken during 1890, 82 in 

 number, young and old, were carefully studied, but in every case save one the females 

 were found to be fertile, and in the majority of cases pregnant. The single excex^tion 

 was an adult cow, probably 5 years old, in which the genito- urinary system had 

 failed to develop, the ovaries and uterus being no larger than in a yearling,' The 



1 This animal was killed on St. Paul while I was absent on St. George, and was examined by Dr. 

 Otto Voss, the resident physician, aud by Dr. Jordan. 



5974— PT 3 4 



