254 



ZOOLOGY. 



stated, the blastoderm has increased to about three-quarters 

 of an inch in diameter. A surface-view is shown in fig. 



fl/JX/A/ 



HEAD fOt.0 



f M B R Y 



Fig. 181. DIAGRAMMATIC MEDIAN SECTION or EMBRYO GBICL 

 (First Stage.) 



Fig. 132. DIAGRAMMATIC TRANSVERSE SECTION or EMBRYO CHICK. 

 (First Stage.) 



129, and a transverse section through one of the somites in 

 fig. 130. Comparing this with fig. 120, the corresponding 

 stage in the frog, we can see that if in the latter we slit 



