^jo DISCOVERY REPORTS 



the numerous spermatozoa are to be seen only in one tubule out of half a dozen or 

 more, whereas in the active testis they are uniformly distributed as a result of active 

 proliferation throughout the tubules. 



Since this indication of a male sexual season is of considerable importance in its 

 relation to the problem of the breeding season of whales, it will be worth while to make 

 a systematic examination of the data. The following is an account of the testes of whales 

 taken in different months, which have been examined histologically. 



(rt) Blue Whales 

 Jamiory. Two specimens. Both with tubules lightly filled with cells, but with rather 

 few spermatozoa. 



February. Four specimens. In three of these the tubules were mostly still in a 

 practically immature condition. In the fourth there were few spermatozoa and there 

 were empty spaces in some of the tubules. 



March. One specimen. Empty spaces in the tubules and few spermatozoa. 



April. Six specimens. In two of these the spermatozoa were not many and in one 

 there were empty spaces in the tubules. In the other four the tubules were packed 

 with nuclei and spermatozoa were numerous— not appearing in small groups here and 

 there in an odd section of a tubule, but everywhere. The appearance of the sections 

 suggested a general and uniform proliferation of germ cells, and a production of 

 spermatozoa all along the tubules. 



May. Two specimens. In one of these the sperm.atozoa were numerous, and the 

 tubules, though small and distorted, seemed well filled with cells. In the other, part 

 of the section was similar to the most active specimens, but the rest of the tubules 

 were emptier. 



June. No specimens. 



July. Four specimens. One of these had a moderate number of spermatozoa, but 

 there were few in the others, and none of the tubules contained a noticeably large 

 quantity of cells. These testes seemed to have reverted to the more passive condition. 



August. Two specimens. Both with few spermatozoa and with rather empty tubules. 



September. Four specimens. One with a moderate number of spermatozoa and the 

 rest with few. All had rather empty tubules. 



October. Three specimens. Few spermatozoa in any. In one most of the tubules 

 were immature, in another they were small and distorted, and in the third they were 

 loosely filled with cells. 



November. Five specimens. A moderate number of spermatozoa in one but very 

 few in the rest. In the former the tubules were lightly filled with cells. One of the 

 others was similar in this respect, but in the remaining three there were empty spaces 

 in the tubules. 



December. Three specimens. All with very few spermatozoa and with empty spaces 

 in the tubules. 



