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GARY X. CALKINS AND RACHEL C. BOWLING. 



developing zygote. An astrosphere is condensed from the 

 cytoplasmic reticulum at one pole of the nucleus and the nuclear 

 membrane disappears at this region. We did not observe a stage 

 in which a single centriole could be found in the astrosphere, the 

 earliest stage seen being a minute spindle which appeared to be 

 formed in the substance of the astrosphere in the region which 

 had been occupied by the now dissolved nuclear membrane 

 (Fig. i). This spindle enlarges until it occupies fully one half of 

 the diameter of the cell (Fig. 2). The short, rod-shape or slightly 

 curved chromosomes are ten in number. The daughter nuclei 

 when fully divided may be separated by the full diameter of the 

 cell, and remains of the spindle substances trail out behind them 

 marking the path of the spindle (Fig. 3). 



FIG. 3. Two gamonts after first pregametic nuclear division. Smear. Camera 

 lucida. X 900. 



