172 Oscar Riddle 



ing mechanically scattered over the outside oi the plumage). The 

 claws and bills of the birds likewise become highly colored, but one 

 cannot be perfectly certain that this color is not of external origin. 

 Injection of the stain gave very similar results; in these cases, how- 

 ever, a more diffuse color was obtained, no attempt was made to 

 color the feathers and no staining of the intestinal wall was noted. 

 These birds laid down colored fat after having been given the 

 stain by injection into the peritoneal cavity. 



After feeding the stain to turtles one finds but traces of Sudan 

 deposited in somatic tissues. This is undoubtedly due to the fact 

 that they store fat extremely slowly, and that their bodies actually 

 contain but little fat. The further fact of the difficulty or slowness 

 of digestion which the writer (09) has found especially to charac- 

 terize the turtles, may also be important in this connection. 



The subcutaneous fat and the intestinal mucosa were the only 

 parts other than the ova and follicular membranes in which the 

 writer found the stain deposited in turtles . No injection of the 

 dye was attempted m these animals. 



Rabbits apparently ingest Sudan much more slowly than do 

 fowls. Nevertheless, upon continuous feeding red-colored fat 

 becomes visible in all parts of their bodies, subcutaneous fa t every- 

 where, peritoneal and kidney fat, the intestinal wall and corpora 

 lutea. Daddi noted a similar distribution (except in the corpora 

 lutea) in rabbits and guinea-pigs. A similar distribution of color 

 results from the injection of the stain (except for the mucosa). 



The Rate and Conditions of Absorption and Deposition of 



Sudan III 



Almost no attention has been given by previous writers to 

 the rate at which Sudan is absorbed and desposited. Since 

 this really represents the rate at which fat is absorbed and de- 

 posited, it becomes a matter of considerable interest. Similarly, 

 the conditions of its deposition and non-deposition when it is 

 brought within the blood-stream, have nowhere received consid- 

 eration, except, of course, that it has been generally'noted that it 

 is deposited in fats. The writer is able to report approximately 

 correct data on these points as they were obtained in the study 

 of the fowl only. 



