66 II 1 1 \KWMAN 



EXPLANATION OF PLATES. 



PLATE I. 



FIG. i. Egg with large resting nucleus, showing resumption of chemical inter- 

 action between nucleus and cytoplasm preparatory to the formation of the first 

 cleavage spindle. The deutoplasm has been extruded and has been fixed in the 

 form of numerous cytoids (cy) that almost surround the egg. The dense zona 

 peludica (z.p.) encloses both egg and cytoids. The egg shows a zone of unmodified 

 formative protoplasm (f.p.) and a precipitation ring (p.r.), where the changes 

 between nucleus and cytoplasm are most active. Note that each cytoid has a 

 centrally located, deeply staining, mass of granules, which are the deutoplasmic 

 granules of earlier stages and are not to be interpreted as degenerating nuclei. 

 (X 800.) 



FIG. 2. Egg in which the deutoplasm has just been abstricted and has not yet 

 undergone fragmentation to any marked extent. Two nuclei (w 1 and w 2 ) lie side 

 by side giving the appearance of a fertilization stage. It is probable that these are 

 the product of the first maturation division, completed without the extrusion of a 

 polar body. This could readily occur in cases where the maturation spindle occupies 

 a central position. These two nuclei would doubtless form a multipolar spindle 

 like that shown in Figs. 13 and 14 and would probably result in the formation of 

 nests of nuclei, as in Fig. 12. Other labelling as in Fig. i. ( X 800.) 



