423 



arteries are larger than in the preceding stage, and the two vessels 

 are nearer each other at their origins. 



It may be safely stated, that at least small dorsal remnants of 

 the first and second arches persist up to this stage. A definite ex- 



\-^'' 



Fig. 14. Reconstruction of Aortic arches in Pig embryo of 23rd (?) day. 

 )x( about 18. a.s. subclavian artery, x point of union of 4th arches. Other reference 

 marks as in previous Figs. 



