PLATE 1 



EXPLANATION OF FIGURES 



The figures were drawn with the camera lucida at stage level with Zeiss 

 apochromat 2 mm. oil immersion obj. and the compensatory ocular 6. 

 The figures represent outer parts of the external sheet of the allantois. 



1 Normal allantois at the tenth day of incubation. 



2 Normal allantois at the fifteenth day of incubation. 



3 Cornification of the ectodermal layer in the allantois at the fifteenth 

 day of incubation around the graft made at the eighth day of incubation. 



ABBREVIATIONS 



Ect., ectoderm of the serosa Msc, mesenchyme 



E.ect.c, epiectodermal capillary net S.v.ect., subvascular ectoderm 



Hbl., hemoblast v., vessel. 



I.ect.c, intraectodermal capillary ^ 



net 



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