410 



DISCOVERY REPORTS 



of the unfertilized ovum in whales. In other animals, however, it takes place rapidly, 

 and if the animal is polyoestrous, the corpus has become functionless in time for the 

 ' ripening of follicles for the next oestrous period (Marshall, 1925, p. 48). 



LENGTH OF WHALE IN METRES 



Fig. I. Fin whales, females: Season 1929-30. Frequency of half-metre lengths. 

 Immature whales. Sexually mature whales. 9 Physically mature whales. 



The length of time the corpus luteum can be recognized in the ovaries is discussed 

 by Marshall (1922, p. 147). In the human female the corpus is reduced to an insigni- 

 ficant scar two months after ovulation. In the sow, Corner (1925) found that corpora 

 lutea from one ovulation overlapped those of an earlier ovulation during any one 

 sexual season. Donaldson (1924) gives figures which show definitely the accumulation 

 of corpora lutea with age in the rat (Table X, p. 39). Our own work, as stated on 

 pp. 394-6 of the Report (1929), indicates that, by careful examination of the ovaries 

 of whales, traces can be found of all the ovulations that have occurred since the sexual 

 maturity of the animal. 



It will be seen later that this view is upheld by the facts of physical maturity. One 

 example may be cited. During season 1929-30 two female Fin whales (Nos. 2765, 



