THE DUCTLESS GLANDS OF ALLIGATOR 

 MISSISSIPPIENSIS 



By a. M. REESE 



west virginia university 



(With Three Plates) 



Although several workers have investigated certain of the ductless 

 glands of reptiles, very little has been done upon these glands in the 

 Crocodilia ; so it has seemed worth while to work out the main fea- 

 tures in the gross and microscopic structure of these organs in the 

 alligator. Live animals from 2 to 3 feet long were obtained from a 

 regular dealer and the glands were removed, fixed with various re- 

 agents, sectioned, and stained with the usual stains, mostly haem- 

 atoxylin and eosin. Most of the researches of the author upon the 

 Crocodilia have been made possible by grants from the Smithsonian 

 Institution, the Carnegie Institution of Washington, and the Elizabeth 

 Thompson Science Fund. 



THE ADRENALS 



According to Swale Vincent (11), the first definite description, 

 with figures, of the adrenals was written by Eustachius in 1563; but 

 so little attention was paid to these organs that Fabricius, as late as 

 1738, makes no reference to them. 



At the present time, although the literature is very extensive, but 

 little work has been done upon the anatomy of the adrenals in the 

 Reptilia and almost nothing upon those of the Crocodilia. In man 

 the cortical portion of the adrenal makes its appearance, in embryos 

 of about 6 mm. in length, as a series of buds from the coelomic 

 epithelium in the dorsal body wall, which later fuse to form a mass 

 on each side of the base of the mesentery. The medulla of the adrenal 

 arises, at about the same time, from the neural crest of the embryo 

 in connection with the origin of the sympathetic nervous system, the 

 " sympathochromaphil " tissue. Later the chromaphil tissue differ- 

 entiates from the sympathetic nervous tissue, and by the time the 

 embryo is 19 mm. in length the chromaphil bodies have begun to 

 penetrate the above-mentioned cortical masses. At 9 or 10 cm. the 



Smithsonian Miscellaneous Collections, Vol. 82, No. 16 



