328 



n. c 



.- -t- 



n. cJi, _ 



al. <:.-,.. 



at. c-._. 



ij" 



c. V. a. 

 ^a. 3. 



^va 3. 



z\ 



EE. 



y n. c. 



n. ch. 



ai. c.__^_ 



S3. ' "ic/.^. 



Figs. 21, 22, and 23, sections through the anterior part of the wing region of a 

 chick embryo of eight days of incubation. Owing to the fact that the heart has by this 

 time passed somewhat backward into the thorax, this section also cuts through the point 

 of origin of the secondary Subclavian from the third arch. The sections, Nos. 1, 4, 

 and 10 on the slide, represent a thickness of 133 Va A' (^ »bout 14). Fig. 24, semi- 

 diagramatic representation of a section through the same region, showing the course of 

 the secondary Subclavian. Keference letters as in preceeding figures. 



fl. cluL_. 



n. ch. 

 . 3. 



al. c. 



3. 



ci a. 



zs. 



cl.a. 



26. 



Figs. 25 and 26, sections through the anterior part of the wing region of a chick 

 embryo of nine days of incubation, showing the almost directly lateral course of the Sub- 

 clavian artery. The sectious, Nos. 3 and 8 on the slide, represent a thickness of 100 /t 

 (x about 18). Reference letters as in preceeding figures. 



