132 DISCOVERY REPORTS 



Sperm whale. The testes were active and spermatozoa were present in some individuals 

 in all these months. In fact, those in which the testes were active tended to out- 

 number those which showed signs of lower activity. It is interesting to note that 

 spermatozoa could be found in the testes of all males at South Georgia and that in 

 many the testes were in full activity, because females are not found in these waters 

 at all, so there could be no question of breeding there. From a teleological point 

 of view this activity in the testes of the South Georgian Sperm whales is quite useless to 

 the species. It is plain, therefore, that any evidence regarding the time of the breeding 

 season must be looked for in the data regarding the female Sperm whale. It can be con- 

 cluded that unless evidence of an unexpected character should be forthcoming at a later 

 date regarding the state of the testes in May, September or December, there is no 

 definite sexual season or cycle in the male Sperm whale, but that breeding is possible 

 at any time of the year. 



THE FEMALE 



External genitalia. The genital groove includes both the anus and the vulva, which 

 are separated within the groove by a fleshy corrugated pad. So striking is this common 

 groove that in the field log books it was noted as the "cloacal groove". The two 

 openings within the groove are about o-2 m. apart in the adult. A large clitoris lies 

 at the anterior end of the vulva. The nipples lie about o- 17-0-2 m. on either side of the 

 fleshy pad which lies within the groove of the adult (Plate IX, fig. i). 



Ovaries. The ovaries of the Sperm whale are very different from those of the Whale- 

 bone whales. The surface of the ovaries is smooth and the old corpora lutea do not 

 usually project above the surface (Plate XI, fig. 4). Old corpora lutea {b, or corpora 

 albicantia) appear as yellowish or dark markings on the surface, with usually whitish 

 triangular ridge-like scars. Corpora lutea of ovulation or pregnancy (corpora lutea a) 

 project from the surface of the ovary but are not constricted off from it by a neck 

 (Plate XI, fig. 5). The weight of the ovary is small: of those examined in non-pregnant 

 whales none weighed over i\ lb. Fig. 37 shows the ovary weight plotted against body 

 length in ovulating and resting non-pregnant Sperm whales. Though numbers are small, 

 a correlation between the two measurements is evident, and the points are noticeably 

 more regularly arranged than in the corresponding graph for Whalebone whales 

 (Mackintosh and Wheeler, 1929, figs. 120, 121). No values for immature whales are 

 available. 



Fig. 38 shows the mean diameter of the corpora lutea plotted against the length of 

 foetus, corpora lutea a (of ovulation and of pregnancy), and the largest corpora lutea b 

 persisting during pregnancy, being separated. The values are much lower than those for 

 Whalebone whales, probably in correlation with the smaller size of the ovaries in this 

 species ; and the limited figures available do not indicate any marked diminution in size 

 of either corpora lutea a or coexisting corpora lutea b up to the time when the foetus 

 measures 3 m. in length. 



Uterus. Very few measurements of the uterus are available. In a lactating female, in 

 which ovulation had not taken place since parturition, and in which the uterus was 



