12 HAROLD H. PLOUGH. 



EXPLANATION OF PLATE I. 



All figures except Nos. i, 6 and 8 from camera drawings made with Leitz 1.5 

 mm. oil immersion objective and 8 compensating ocular. Nos. i, 6 and 8 from 

 living material with 2 mm. objective. 



FIG. i. Resting stage of secondary spermatogonia living cell stained with 

 janus green showing granular mitochondria. 



FIG. 2. First spermatocyte showing chromatin network with cloudy mass of 

 mitochondria and prominent "neutral red granules" in the cytoplasm. 



FIG. 3. First spermatocyte beginning to show the "massive bodies"; mito- 

 some, idiozone and "neutral red granules" visible in cytoplasm. 



FIG. 4. Similar to the preceding, the idiozome shrunken so as to appear in a 

 vacuole because of imperfect fixation. 



FIG. 5. First spermatocyte bouquet stage diplotene threads polarized toward 

 idiozome, chromatoid body visible. 



FIG. 6. Similar to preceding living cell stained with janus green mito- 

 chondria in two masses surrounding a spherical space in which the idiozome 

 (invisible) probably lies, since the diplotene threads are polarized toward it. 



FIG. 7. Diakinesis drawn from a preparation stained with alizarin and 

 crystal violet showing large chromatoid body in a vacuole. 



FIG. 8. Similar stage in living cell stained with both janus green and neutral 

 red, mitochondria and chromatoid body visible. 



FIG. 9. Telophase of first spermatocyte division the chromatoid body passing 

 to one pole. 



FIG. 10. Late telophase of second spermatocyte division spermatid nuclei 

 already formed mitochondria aggregated into the spherical nebenkerns-chroma- 

 toid body in one daughter-cell. 



FIG. ii. Spermatid showing nebenkern and acrosome sphere. 



FIG. 12. Spermatid, tail beginning to elongate, nebenkern divided, chromatoid 

 body passing down close to the axial filament. 



FIG. 13. Group of sperm tails, showing chromatoid bodies just before they are 

 cast off. 



