THE PARS BUCCALIS OF THE HYPOPHYSIS 91 



Albinous tadpoles, on the contrary, reveal notable variations 

 even on surface view from the picture presented by the two 

 normally pigmented types (fig. 39). Although the kidney is of 

 normal size, the adrenal column appears much more slender and 

 more mesially placed than in a normal or thyroidectomized 

 specimen of corresponding or even of inferior size. Not only 

 is the column more delicate, but its caudal extent is somewhat 

 less, its cephalic extent, however, corresponding to the normal. 

 Sudan III does not color the column deeply, while the osmic- 

 bichromate solution produces only a grayish coloration in con- 

 trast to the dark brown of the normal gland. Treatment with 

 potassium bichromate gives an effect nearly identical with that 

 of the normal. We thus have evidence, from surface views alone, 

 which leads us to suspect that the adrenal cortex of the albino 

 is diminished. 



A section study of the three above-described types of animals 

 lends corroborative evidence of an unquestioned nature to that 

 furnished by the surface examination. For such a study it is 

 essential that the technique employed not only preserve the 

 lipoid content of the cortical or interrenal cells, but that the 

 medulla be clearly, although not necessarily differentially, stained. 

 The most satisfactory fixing fluid has proved to be an osmic- 

 bichromate mixture (Flemming's fluid less the acetic acid) which, 

 although blackening the lipoids, does not interfere with the 

 subsequent staining of the other tissues. Curiously, the chro- 

 maffin reaction is not shown when the osmium and bichromate, 

 either mixed together or subsequent to each other, are used. 

 Following fixation, immersion in 50 per cent, alcohol for twenty- 

 four hours deepens the color of the lipoid granules and appears 

 to render them less soluble in the higher alcohols and the clear- 

 ing agents. The sections (5 to 8tJ-) are rapidly run down to 

 60 per cent, alcohol and then stained for two to three hours in 

 Babes' safranin at 36°. After rinsing in alcohol, rapidly de- 

 hydrating and mounting, there is presented a preparation in 

 which the lipoid granules, a few of which have apparently been 

 partially dissolved, are distinctly shown and in which the chro- 

 maffin cells can be unmistakably identified by their red tinge. 



