SECOND HALF OF SECOND DAV 



477 



Fig. 281. 



Transverse sections through a 36 to 38 hour chick embryo. A, Through forebrain ; B, through 

 the pharyngeal membrane ; C, through hindbrain and auditory placodes ; D, through posterior end 

 of heart; E, through the intestinal portal; F, just posterior to E; G, through the fourteenth pair 

 of segments ; H, through the rhomboidal sinus ; I, through Hensen's node ; J, through the primi- 

 tive streak; K, medial longitudinal section of a 36 to 38 hour chick embryo. (This drawing must 

 be studied very carefully and thoroughly to understand the transverse sections which are cut 

 through the levels marked.) 



