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ALBERT H. TUTTLE 
EXPLANATION OF FIGURES 
All figures are drawn with a magnification of 1000 diameters by means of the cam- 
era lucida: Zeiss apochromat 1.5 mm., N. A. 1.30; compensating ocular 6. 
1 "Frontal" view of a resting nucleus. 
2 "Profile" of a resting nucleus somewhat larger and more irregular in shape 
than the average. 
3 Nucleus enlarging and elongating, along with the appearance of the parietal 
ring. 
4 Assumption of the typical fusiform shape, with a tendency toward a reticular 
arrangement of the chromatin granules. 
5 Well developed spireme. 
6 Breaking of the spireme into chromosomes. 
