60 
SPERMATOGENESIS OF NORMAL 
Fig. 7. 
Fig. 8. 
Fig. 9. 
Fig. 10. 
Fig.11. 
Fig. 12. 
Fig. 13. 
Fig. 14. 
Fig. 15. 
Fig. 16. 
Fig. 17. 
X 2000—Synapsis in a primary spermatocyte. The 
sphere shows vacnole-like radiations 
from the, region of the centrosome. 
X 2000—The spirem of a primary spermatocyte. 
X 2000—Primary spermatocyte. The chromosomes 
in the form of long loops. 
X 2000—Primary spermatocyte shortly before di¬ 
vision. 
X 2000—Primary spermatocyte ready for division. 
X 2000—Primary spermatocyte showing divergence 
of chromosomes. 
X 2000—Completion of the division of a primary 
spermatocyte. 
X 2000—Secondary spermatocyte ready for division. 
X 2000—Divergence of the chromosomes in the di¬ 
vision of a secondary spermatocyte. 
X 2000—Young spermatid immediately after its for¬ 
mation through the division of a second¬ 
ary spermatocyte. The tip of the spindle 
and the centrosome persist. 
X 2000—Spermatid in resting condition. 
Fig. 18-26. X 2000—Successive stages in the transformation 
of the spermatid into the adult sperma¬ 
tozoon. 
Fig. 27. X 1800—Mature spermatozoon from the vas deferens 
of the pigeon. 
Fig. 28-31. X 2000—Primary spermatocytes of hybrid pig¬ 
eons showing various types of double 
spindles. 
Fig. 32. X 2000—Cells resulting from the division of a prim¬ 
ary spermatocyte by means of a tripolar 
spindle. 
Fig. 33. X 2000—Primary spermatocyte of a hybrid pigeon, 
showing the unequal division of some of 
the. chromosomes. 
