670 FRANCIS M. BALDWIN 



layer enclosing a conspicuous lumen, but which in no case con- 

 tains colloidal material. 



22. During transformation, because of increase in size of the 

 surrounding structures (especially the laryngeus and sterno- 

 hyoideus muscles) the postbranchial body is flattened laterall}^ 

 and reduced to a sheet of poorly defined cells which now contains 

 no lumen. 



23. The structure and anatomical position of the postbranchial 

 body in the adult is variable. In sections of young adult heads, 

 it is a fairly compact oval body composed of fairly regular cuboidal 

 cells enclosing a spacious lumei;!. In sections of old heads, I was 

 not able with certainty to locate the structure. 



24. The carotid gland and epithelial bodies in Amblystoma 

 begin their development at the time of metamorphosis. There is 

 no evidence to show that the epithelial cells of the degenerating 

 gill-pouches are concerned in its formation. 



25. The anlagen of the epithelial bodies (two on either side) are 

 irregular longitudinal sheets of entodermal cells (remnants of the 

 ventral portions of the fourth and fifth visceral pouches) extend- 

 ing caudad from points where the afferent branchial arteries 

 enter their corresponding gills in the early transforming stage. 



26. As transformation proceeds, the sheets of cells become 

 resolved into compact oval bodies (two on a side). In the late 

 transforming stage, these lie one behind the other, close caudad 

 to the carotid gland, each being enveloped by connective tissue. 

 They now take a position lateral to the second aortic arch. 



27. The two epithelial bodies in the adult lie imbedded in con- 

 nective tissue on the side of the neck in the region just below the 

 thymus gland, just caudad to the carotid gland, although their 

 position may vary slightly in different individuals. 



28. The blood supply of the epithelial bodies is from small twigs 

 of the second aortic arch, and from the external carotid artery, 

 while they are innervated (probably) by a small ramus from the 

 vagus ganglion. 



