92 PIGMENTARY GROWTH AFTER ABLATION OP 



Further evidence that this identification is not incorrect was 

 secured by fixation in M tiller's fluid followed by a prolonged 

 mordantage in potassium bichromate, the sections then showing 

 the reticular fat-free cortical cells and the browned medulla. 



By the employment of these two methods it can be readily 

 determined that this longitudinal cell mass, aside from blood- 

 vessels, connective tissue, and an occasional readily identified 

 nephric tubule, is composed entirely of adrenal cortex and 

 medulla. 



The cortical cords, varying somewhat in width, are usually 

 formed of three or four cell columns. They measure in the 

 normal animal from 30 to 48^ in diameter, an average of 36. 6 n. 

 In the thyroidectomized specimens they are from 24 to 56^ 

 in diameter, an average of 36.5[x (table 8). The individual 

 cells composing these cords are of approximately the same size 

 in the two animals, in the normal averaging 15.1[x in diameter, 

 in the thyroidectomized specimens 16.5^. These cells are com- 

 posed of a mass of lipoid granules imbedded in a cytoreticulum 

 and surrounding a nucleus approximately centrally placed. This 

 structure, then, after the osmic-bichromate solution gives a 

 coarse, dark granular appearance, or after ordinary fixation 

 and treatment with fat solvents reveals a delicate reticular cell. 



If we compare these cortical cords, or cells, of the albino with 

 those of the unoperated tadpole (figs. 38 to 41), we find that 

 they are decreased in size in the former. The cords (in a 55-mm. 

 albino) vary from 24 to 32^ in diameter, an average of 23.7[x, 

 a reduction of approximately 33 per cent, from the normal. 

 The cells vary from 12 to I6yi in diameter and average 12.7[x 

 (table 8), a reduction of approximately 25 per cent, from the 

 normal. It is difficult to determine, because of their profuse 

 branching, whether the cords are actually reduced in number in 

 the albino, but apparently this is the case. 



The interrenal cells of the normal or thyroidless animal are 

 browned by osmic; those of the albino assume a gray tone (figs. 

 38, 39). This would appear to be due to a different reaction 

 of these granules and not to their volume, since the granules of 

 both types of specimen are blackened by subsequent treatment 

 with a low grade of alcohol. 



