IS2 DISCOVERY REPORTS 



blood vessels which mark the sites of previous placentation. It is reasonable to conclude 

 that such structures will be most persistent in animals whose powers of recuperation 

 have been impaired by age, and the five are all animals of large size (nos. 478, 497, 499, 

 527 and 532). These structures have also been found in eighth and ninth year animals, 

 one of each group. 



No. 478 shows the most definite signs of failing activity. The uterus was hard and 

 small, although the outside diameter of the cornua was 1 -8 cm. The right ovary appeared 

 at first sight to have no follicles, but search produced three which were very small and 

 in the left ovary also a few small follicles were present. Each ovary contained the 

 remains of a corpus luteum, one being more degenerate than the other, and in addition 

 the left ovary had a small corpus luteum of 1 cm. diameter which shows few signs of 

 luteinization, under the microscope. 



DISCUSSION 



After the breeding season the bulls which have taken part in it are exhausted and 

 there begins a period of partial inactivity, much of it spent in sleep and lasting from the 

 end of the breeding season, that is, the latter part of February, to July. 



It is very probable that there is some sort of seasonal rhythm, since all bulls are quiet 

 at this time, although glandular activity is not necessarily suspended, e.g. no. 431. The 

 shedding of the old coat and its renewal take place at this time. Four months is a 

 sufficiently long time for the rest and in July the bulls begin again to take an interest in 

 the cows, as is shown by their efforts to keep females from escaping into the water when 

 they try to go thither of their own accord or, sometimes, when they are alarmed, but 

 this retentiveness is not marked with the fervour of the breeding season. The tendency 

 to retain cows becomes more and more marked as winter gives place to spring and the 

 rutting season approaches. By the end of August or the beginning of September bulls 

 were noted as "very pugnacious" and as early as 13 September a bull was seen to make 

 prolonged although unsuccessful efforts to cover a cow. 



Further attempts have been observed in the first part of December and the first 

 consummations were seen about the middle of the month (but see p. 153). 



The earliest newly born pup was recorded on 16 November, but the middle of 

 December must be regarded as the beginning of the pupping season. Production is 

 slow at first but rapidly accelerates and attains its maximum in the first half of January. 

 January 23 is the last definite date for a birth, but a pup with a piece of umbilical cord 

 attached has been seen on the 27th, and a placenta has been found on the beach on the 

 28th, in spite of the abundance of carrion-eating birds which usually dispose of such 

 debris as soon as it appears. 



There is some indication that births may take place occasionally at times more or less 

 remote from the recognizable pupping season. No. 1001 was killed in July and had been 

 pregnant so recently that the uterus had not returned to the non-gravid condition, the 

 outside diameter of the lately pregnant cornu being approximately 4 cm. ; it is somewhat 

 distorted. 



