VIRILITY OF YOUNG BULLS. 45 



Among such questions are the ages at which the males and females begin and cease 

 to breed, the frequency of births, the alleged frequent occurrence of " barren cows," 

 the necessary proportion of the two sexes, and their natural proportions at birth. 

 Much of this information, and particularly that which depends on the study of the 

 reproductive system, could not have been secured in the better days of the Pribilofs 

 without killing many females and creating great disturbance on the rookeries. The 

 great destruction of the females at sea and the consequent thinning out of the rook- 

 eries has rendered it possible to get about the breeding grounds more readily than 

 formerly, while by obtaining from pelagic sealers the bodies of skinned seals extensive 

 series of females of all ages were secured for examination.' 



Mr. 0. H. Townsend, to whom belongs the credit of having inaugurated this 

 important line of work ^ with its incontrovertible evidence, collected and examined 

 the ovaries of 106 seals in 1895, and during the present season (1896) we procured 75 

 more, while these were supplemented by others obtained from paps and females of 

 various ages killed for examination. From this material data were obtained which 

 rendered it possible to substitute facts for probabilities and to refute some of the wild 

 assertions that had found their way into print. 



As stated by Elliott, the testes of the young male are inguinal, descending into 

 the scrotum toward the end of the second or commencement of the third year;^ and 

 Mr. Andrew Halkett has found living spermatozoa in a 3-year-old male. The males 

 are thus occasionally capable of procreation at the age of 3, but they are rarely able 

 to enter the rookeries before the age of 6, while the majority of bulls on the breeding 

 grounds are 7 years old and upward. The failure of the young bulls to enter the 

 rookeries is not due to any lack of desire, but simply because they have not attained 

 their full growth and are not large and strong enough to fight their way in; and here 

 again " natural selection " works to the advantage of the fur-seal race by permitting 

 only the full-grown, vigorous males to possess harems. Many of the younger bulls 

 obtain .cows and get their first experiences in the art of running a harem after the 

 rookeries have expanded and the young females have made their appearance, and it 

 is very amusing to see these youngsters endeavoring to assame the airs and manners 

 of veterans. At this time, too, the idle bulls, which were unable to obtain cows earlier 

 in the season, secure a cow or two, either young or old, and establish small and tem- 

 porary harems — temporary because there are no young to cause the cow to return after 

 she has again taken to the water. 



' In this connection I would like to express my obligations to Capt. W. H. Roberts, as well as to 

 the officers of the B,us%, for the cordial assistance rendered in securing material and for the interest 

 taken in the work. It is not a pleasant, and often no easy, task to transfer several boat loads of 

 greasy, bleeding seal carcasses from the decks of a sealing schooner to the revenue cutter, but the 

 work was most cheerfully done, and the material thus secured was invaluable, 



2 Mr. Townsend made, a commencement of this work in 1892, but it was not prosecuted vigorously 

 until 1895. 



^ A curious feature in the seals is the voluntary or involuntary withdrawal of the testes from the 

 scrotum. From the study of a few individuals it seemed probable that, as in squirrels and many 

 other animals, the testes were completely retracted at the end of the season ; but more extended 

 observations by Mr. Clark and myself showed that while this was to some extent true, much depended 

 on the position of the animal, and also that they seemed to be under the animal's control. When a 

 seal lies on his back, tlie testes are pressed backward and appear; when he rolls over and starts to walk 

 away, they are wholly or partially withdrawn, thus furnishing a safeguard against injury when the 

 animal is running about over rooky ground. See also page 18. 



