48 THE FUR SEALS OF THE PRIBILOF ISLANDS. 



Up and lying down as sheep do. In the case of three births witnessed a copious discharge of water 

 preceded delivery. The cow shows no' disposition to lick or otherwise dry her pup. She fondles and 

 calls over it, smelling of it, and will lift it oat of the way of danger, taking it hy the skin of the back 

 as a eat would her kitten. Soon after delivery the mother draws the pup toward her breast as if to 

 have it suck, and it is not long before the pup is able to do so. In the case of one birth witnessed the 

 cow by swinging about immediately separated the pup from the placenta, which was not delivered 

 within half an hour after the birth of the pup. That there is difficulty in breaking the umbilical cord 

 in some cases is evidenced by the fact that one pup was found imprisoned in the rocks attached by an 

 r.n usually thick cord to a rotting placenta. The pup, though a week or more old, had not moved 

 from its place; its flippers were white and it was unable to use them when 'released. It had pi-ob- 

 ably not moved from its place since birth. Another pup, strong and healthy, was seen walking about 

 with the dried placenta attached to it by a very thick cord which greatly impeded its movements. 



While the female is sexually mature at the age of 2, the uterus and ovaries do 

 not attain their full development until some time later, the difference in size between 

 the ovaries of the 2 year-olds and those of the older females, though slight, being 

 quite noticeable. There is, however, a considerable amount of individual variation 

 in the size of these organs not dependent on age, and it sometimes happens that the 

 ovaries of a breeding female are smaller than those of a 2-year-old, The following 

 measurements, taken from carefully preserved alcoholic specimens, may be taken as 

 giving the average size of the ovaries : Two months, 10 by 13 mm. ; one year, 15 by 17 

 mm. ; two years, 22 by 25 mm. ; adults, 23 by 25 and 25 by 28 mm. 



As the development of the fetus is extremely slow while the cow is nursing, the 

 embryo is consequently so minute during August and September as to escape detec- 

 tion, unless carefully looked for under favorable circumstances and with the most 

 approved appliances. The question as to whether or not a female has been impreg- 

 nated therefore depends on the condition of the ovary, and it might naturally be asked 

 what reason there is to suppose that a scar on the ovary is not m^ely due to the 

 rupture of a Graafian follicle. In answer to this it may be said that of the 146 ovaries 

 of adult nursing females, examined by Mr. Townsend and myself, all bore a single old 

 scar on the ovary corresponding to that branch of the uterus in which delivery had 

 last taken place. In 78 specimens examined by Mr. Townsend in 1895 there was an 

 unquestionably fresh scar on 68, and on reexamination 7 of the 10 doubtful cases 

 proved to have been impregnated. The exact condition of the remaining 3 will never 

 be known, as they were not preserved, but they, too, may have been impregnated. 

 The 68 specimens collected in 1896, with one exception, bore a recent scar on the ovary 

 functional for the season, although in these instances the fact was not apparent on a 

 first examination." In specimens obtained early in September, the corpus luteum ai^d 

 corresponding branch of the uterus had increased in size, showing clearly that 

 impregnation had taken place, and since in no case did an ovary bear more than one 

 scar it is not assuming too much to say that in the fur seal ovulation is practically 

 synonymous with impregnation. That this should be so is not surprising when it is 

 considered that a female, after entering a harem, is held there by the bull until he is 

 satisfied that she may properly be allowed to leave; that back of the harem and along 

 the water front are idle bulls waiting for stray females, and that finally when the 

 harem system is relaxed there is an influx of young bulls who before this time could 

 not enter the rookeries, and who would be likely to discover if any female were still 

 unimpregnated. In the possible event of a female escaping impregnation when the 

 first Graafian follicle reached maturity the next advanced follicle would ripen, and as 



' In all doubtful cases the specimen was preserved and subsequently examined in company with 

 Dr. William Gray, of the Army Medical Museum, 



