PLATE XI 



Fig. I. Sperm whale. Microphotograph of section of completely inactive 

 testis tissue. ■- 50. 



Fig. 2. Sperm whale. Microphotograph of section of adult testis, active 

 stage, tubules full of dividing cells, x 50. 



Fig. 3. Sperm whale. Microphotograph of section of adult testis, 

 resting stage, tubules with large clear spaces, x 50. 



Fig. 4. Sperm whale. Ovaries of non-pregnant Sperm whale. Note 



smooth surface. Approximately -] natural size. 



Fig. 5. Sperm whale. Ovaries of pregnant Sperm whale. The corpus 

 luteum a, at the top on the right hand, is not constricted off by a 

 neck. Corpora lutea b appear as 1 ow swellings. Approximately ^ 

 natural size. 



