Early Development of the Plen's Egg. 



125 



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Fig. 3. — Enlarged di'a\Ying of the cleavage memlirane of the preceding 

 figure, cm., cleavage membrane; in. p., membrane plate; v., vitelline mem- 

 brane. X 525. 



Fig. 4. — Enlarged drawing of the extreme left end of the section shown in 

 Fig. 18. This shows a supernumerary sperm nucleus, s.p., al)out which cell 

 formation is attempted, as evidenced by the horizontal cleft situated just 

 above the nucleus. X 525. 



Fig. 5. — Diagram of an unsegmented blastodisc showing the distribution 

 of twenty-four sperm nuclei. This egg was removed from the oviduct about 

 two and a half hours after the estimated time of fertilization, when it was 

 eleven inches from the infundibulum. See Table 1, hen No. 1. X 18. 



