NO. l6 DUCTLESS GLANDS OF THE ALLIGATOR REESE 3 



The cortical and medullary (or chromaphil) cells are easily dis- 

 tinguished from each other in material fixed in chromium salts, by 

 the fact that the latter become colored from brown to bright yellow 

 and stand out in strong contrast to the paler cortical cells. 



In a medium-power view of the entire cross section of the gland 

 (fig. 2, pi. i) the chromaphil cell groups are seen to be much more 

 numerous near the periphery of the gland, especially on the dorsal 

 side, under the capsule, than in the more central region. The region 

 shown in figure 3 is about mid-way between the center and the 

 periphery. 



The cortical cells form a compact mass, near the periphery, the 

 interspaces of which seem almost completely filled by the medullary 

 or chromaphil cells ; but towards the center they separate into thick 

 irregular columns or strands (fig. 2, cc) with wide interspaces 

 (fig. 3, is). Some of the chromaphil masses seem to lie imbedded in 

 the sides of these cortical columns rather than in the interspaces. The 

 intercolumnar spaces are largely occupied by capillaries or sinuses in 

 which blood corpuscles are seen. 



As shown in figure 3, the cortical masses are made up of clear, 

 finely granular, irregular cells, whose walls are difficult or impossible 

 to see, in many places. The nuclei are of average size, usually 

 spherical or oval in shape and are rather finely granular. 



Each column of the cortex seems surrounded by a sort of basement 

 membrane or pavement epithelium (en) in which occasional flattened 

 nuclei may be seen. This epithelium represents the endothelium of 

 the capillaries of the intercolumnar spaces mentioned above. There 

 is apparently no other intercolumnar connective tissue. 



The medulla or chromaphil material, as has been said, consists of 

 masses of yellow or brown cells (in tissue fixed in chromic acid) 

 lying between the cortical columns (figs. 2 and 3, inc). These cell- 

 masses vary not only in color, the yellow cells mostly lying peripheral 

 to the brown, but also in size and shape. The outlines of their con- 

 stituent cells are even harder to see than those of the cortical cells, 

 but the cells are easily distinguished from the adjacent cortical cells 

 by their coloring. The nuclei apparently do not differ from those of 

 the cortical cells; they often lie so close together that, if each one 

 represents a cell, the medullary cells must be somewhat smaller, as 

 a rule, than those of the cortex. In Uromastix, according to Vin- 

 cent (11), the chromaphil cells are larger than the cortical. The 

 chromaphil cells are more distinctly and more coarsely granular than 

 are the cortical cells. No difference could be determined with cer- 

 tainty between the adrenals of an animal after a prolonged fast and 



