PLATE 1 
EXPLANATION OF FIGURES 
Figures 1 to 19 are from Plethodon cinereus; figures 20 and 22 are from Dis- 
sosteira carolina; the others are from Rhomaleum micropterum. 
1 Late primary spermatocyte. (Flemming without acetic-hematoxylin. ) 
2 Metaphase first spermatocytedivision. (Cajal’s formol-uranium nitrate.) 
3 Secondary spermatocyte. (Flemming without acetic-hematoxylin.) 
4 Spermatid nucleus showing group of granules encircling the acroblast. 
(Cajal-gold chloride-hematoxylin.) 
5 Spermatid. Early formation of acrosome from acroblast. (Modified 
Kopsch.) 
6 Spermatid. Later stage in formation of acrosome. (Cajal-gold chloride— 
hematoxylin.) 
7 Spermatid. Final stage in formation of acrosome. (Cajal-gold chloride- 
hematoxylin.) 
8 Spermatid. Fixation of acrosome. (Champy-hematoxylin.) 
9 Spermatid. Casting off of the acroblast (Golgi remnant). (Cajal.) 
10 Spermatid. Showing proximal (?) centriole divided into two equal 
parts. (Champy-hematoxylin.) 
11 and 12 Spermatids. Progressive stages in the elongation of the nucleus. 
Figure 12 shows only a portion of thenucleus. (Cajal-gold chloride-hematoxylin.) 
13 and 14 Basal end of two adjacent spermatid heads in successive stages of 
differentiation, to show separation and fusion of the components of the proximal 
(?) centriole. (Champy-hematoxylin.) 
15 Basal end of spermatid nucleus, to show continued separation of the 
components of the proximal (?) centriole. (Champy-hematoxylin. ) 
16 to 18 Oblique sections through the basal end of the spermatid head, to 
show possible origin of the membrane filament. (Champy-hematoxylin.) 
19 Late stage in the differentiation of the spermatid. Elongation of the 
ring centriole. (Champy-hematoxylin.) 
20 Second maturation division. Late telophase. (Cajal.) 
21 Cross-section through the nebenkern just prior to the complete disap- 
pearance of thechromophilicsubstance. (Flemming without acetic-hematoxylin.) 
22 Spermatid. Development of the central substance in the nebenkern. 
(Cajal.) 
23 and 24 Spermatids. Stages in the development of the acrosome. (Flem- 
ming without acetic-hematoxylin. ) 
25 and 26 Spermatids. Later stages in the transformation of the acrosome. 
(Flemming without acetic-hematoxylin.) 
