Early Development of the Hen's Egg. 



133 





27 



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i;jj-niicmmj;i!U:mi^^''',''^-**^-'^^^^^ 





•• • ••• « ■•• Too o o • o *o ■-■"-. 



'::]'.-:'.\°.\\'^°''l''<,c-''.v:°°y' ^^m^^ 





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 „ , „_„&<* -J o*>a ••• ••• 



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28 



Fig. 27. 

 shown iu 

 gin of the 



Fig. 28. 

 shown in 



Fig. 29. 

 sistei* nuc 

 X 139. 



29 



men 



The anterior end of a section located to the right of the one 

 the preceding flgnre. This gives the details of structure of the mar- 

 disc. Some of the nuclei are taken from adjacent sections. X 139. 

 — Section of a marginal cell from the same series as the section 

 Fig. 31. m.c.n., marginal cell nucleus, undergoing division, x 139. 

 — Another marginal cell from the same series, showing how the 

 lei have migrated apart, m.c.n., sister nuclei of the marginal cell. 



30 



Fig. 30. — Surface view of a blastoderm of an egg taken from the shell-gland 

 seven hours after fertilization (see Table 1, hen No. S). There are 31 mar- 

 ginal and 123 central cells, or a total of 154 in the surface view, m., short 

 radial furrows at the margin. X 18. 



