336 CHARLES PACKARD 



across the entire space and reaches the membrane just below the 

 sperm (fig. 4). The sperm enters somewhat earher than in the 

 controls. The cone does not sink back into the egg protoplasm 

 but remains elevated and the sperm penetrates throughout its 

 entire length (fg. 5). In some instances the sperm does not 

 enter ^at all. 



The egg develops normally £i,s far as the first metaphase. In 

 some instances development up to cleavage is normal, but such 

 eggs do not develop far, for they die before reaching the trocho- 

 phore stage. Of the abnormally developing eggs about 20 per cent 

 show a curiously small polar spindle. The whole figure is crowded 

 to the periphery of the egg. The polar body, however, is normally 

 extruded and the second maturation spindle is apparently normal. 

 In about 40 per cent of the eggs the centrosomes of the first 

 polar spindle divide to form a tripolar or multipolar spindle 

 (figs. 6 and 7). The chromosomes are perfectly normal and the 

 asters are well developed. But in such cases the first polar body 

 is not extruded. The chromosomes remain in the condensed 

 condition for a considerable period, after which, those nearest 

 the periphery are extruded in the second polar body. The 

 reason for believing that this is the second and not the first polar 

 body is that immediately after its extrusion the chromosomes 

 become vesicular, just as they do in normal eggs after the second 

 polar body has been given off. The mechanism involved in the 

 extrusion of those chromosomes is not clear since in no case 

 have I been able to find any spindles. Either the stage during 

 which they are present has been passed through very quickly, 

 or else the fibers do not stain; figures 8 and 9 show this condition. 

 In figure 8 only a few chromosomal vesicles are shown. The 

 polar body is unusually large, and contains little chromatin. 

 Figure 9 shows a later stage. The polar body has formed 

 completely and the remaining chromosomal vesicles, whose 

 position indicates that they were lying in a tripolar spindle, are 

 now distinct. There are about 28 karyomeres in the vesicles. 



If the sperm fails to enter, development proceeds in a very 

 different way. As before, multipolar spindles form at the first 

 maturation division. The first polar body is suppressed, and 



