Fig. 29 Centrifuged four hours (2000 revolutions per minute); fixed at once. 
The yolk was thrown out into lobes, one of which has been detached; the smaller 
nuclei are in the smaller cells. 
Fig. 30 Centrifuged ten minutes in gum arabic during first cleavage; fixed four 
hours later. Asters and spindles are proportional to the volume of the cytoplasm. 
Fig. 31 Centrifuged four hours during the first cleavage; fixed six hours later. 
Most of the cytoplasm is in the smaller macromeres and these have divided earlier 
than the larger ones. At least one-half of the cytoplasm in the larger macromeres 
goes into the micromeres. The first cleavage is not strictly meridional and the 
spiral form of division is lost. (For explanation of figs. 32 and 33, see p. 98). 
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