EXPLANATION OF PLATES 
All drawings were outlined with camera lucida; 2-mm. oil-immersion objective 
used, ocular 12; hence are of the same magnification. Plates 1, 2, and 3 have been 
reduced one-third. 
PLATE 1 
EXPLANATION OF FIGURES 
1 Primary spermatogonium surrounded by follicle. Note polymorphic 
nucleus, i.e., chromosomal vesicles. From first-year larvae. 
2 Diagram of early division prophase of primary spermatogonium. The 
chromosomes appear in vesicles which make up the entire nucleus and give it the 
lobulated appearance. 
3 Diagram of later prophase. Chromosome vesicles have disappeared. 
4 and 6 Equatorial plates showing twenty-eight chromosomes. Note Chro- 
mosome pair marked A. The peculiarity of an end-piece attached by a non- 
staining area is constant. 
5 Odd type of spermatogonial prophase chromosomes may appear in best 
fixed material. Chromosomes appear as solid balls. Abnormal cell evidently 
degenerating. 
7 Odd cell division. Spindle oriented in short axis of cell. 
8 Resting nucleus after last spermatogonial telephase. Note the chromatin 
iblocks and linin fibrils. Larvae 45 mm. total length. 
9 Preleptotene stage showing resolution of the chromatin blocks into fine 
threads. Larvae 40 mm. total length. 
10 Large cell with leptotene threads. Note the chromoplasts with attached 
fibrils. 
11 Amphitene nucleus. Pachytene loops at proximal pole, unpaired lepto- 
tene filaments at distal pole. This cell illustrates the formation of the pachytene 
bouquet. See plate 5, fig. 39. Larva 45 mm. total length. 
12 Isolated pachytene threads showing unpaired leptotene filaments at dis- 
tal ends. Compare with figures 36 to 39, plate 5. 
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