ON SPERMATOGENESIS IN THE RAT. 
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Fig. 19. Group of young spermatozoa, stage of Fig. 8. (The middle 
piece of the spermatozoa has now reached its full length.) 
Fig. 20. A group of spermatozoa, showing the separation of the seminal 
granules. 
Fig. 21. — A supporting cell casting off its spermatozoa. 
Figs. 22 — 24. — Osmic acid preparation. Separate spermatozoa. 
Fig. 22 ( a — l). A series showing the development of young spermatozoa, 
detached from the groups. The gradual transformation of the nucleus 
into the spermatozoon head is especially shown. 
Fig. 23. A spermatozoon at the stage of Fig. 18. 
Fig. 24. Spermatozoa almost fully developed, a. The residual globule is 
still attached, b. This is thrown off, but the head of the spermatozoon 
is not yet free. c. There is only a small granule remaining at the 
junction of the head and middle piece. 
Fig. 25. — A spermatozoon from the epidydymis of the Rat, stained with 
gold, showing the spiral filament. 
