142 DISCOVERY REPORTS 



The heaviest individual testis was 57 g. (no. 449) and the lightest 36 g. (no. 469). The 

 organs of a pair may differ by as much as 7 g. (no. 469), the weights being 36 and 42 g. 

 There is no indication of seasonal variation in size or weight. 



Histology 



The results of microscopical examination of the male reproductive organs may be 

 summarized as follows, the figures in brackets showing the number of specimens in each 

 month represented. 



March (2). No. 503. Spermatids few or absent and cellular debris in the seminiferous 

 tubules, no sperms found. The nuclei of the large cells which occur are dark-staining 

 and thus contrast with the " winter spermatogonia " described by Courrier in Chiroptera 

 (Courrier, 1923, 1 and 2) which are pale although large: the otarian cells are more 

 reminiscent of the "plasmodes spermatocytaires ou teratocytes seminaux" of van 

 Beneden's manuscript to which Courrier refers (Courrier, 1927). 



No sperms were found in the epididymis of no. 503. I consider this animal to have 

 been exhausted by the exertions of the breeding season which had recently terminated. 



No. 431. Spermatids are plentiful but sperms are very few; "teratocytes" occur. 

 There are no sperms in the epididymis. Beginning of recovery from the sexual season. 



June (2). Spermatids are present in both and a few sperms are being produced, 

 "teratocytes" are present in no. 443 and doubtfully in no. 449. No. 443 has many 

 sperms in the epididymis, no. 449 has none there but shows them in the vas deferens. 



July (1). No. 464. (PI. XXXI, fig. 1.) Even spermatocytes are becoming detached 

 in this testis, " teratocytes " are present and there are a very few sperms in the epididymis. 

 The testes were of a yellowish colour when fresh and the general appearance of the 

 creature, which was in poor condition, suggested a lack of vitality but there was no sign 

 of organic disease. The skull shows that this was an animal of somewhat advanced age 

 but there is no definite evidence to show that the condition was one of senility. 



August (2). Nos. 469, 500. These resemble one another, there is little spermatogenesis, 

 "teratocytes" are present, and sperms were found in both epididymes but not in great 

 quantity. 



September (1). No. 471. (PI. XXXI, fig. 2.) Spermatogenesis is proceeding actively 

 and in almost every tubule of the testis, no "teratocytes" were seen and sperms are 

 plentiful in the ducts. 



October (1). No. 498. Spermatogenesis in progress, free sperms may be found in the 

 seminiferous tubules and are abundant in the epididymis. 



December (1, no. 479) and January (1, no. 415) are alike. The testes are in full activity 

 and the epididymes contain a plentiful supply of sperms. 



Comment. No. 503 was killed immediately after the breeding season, and it will be 

 observed that no sperms were found ; but in no. 43 1 , which was killed only a fortnight 

 later, sperms were present in the testis but not in the epididymis. In June, July and 

 August sperms are to be found in the ducts as well as the glands, but in September there 

 is initiated a marked increase in activity, which is very naturally continued into the 



