Sudan III in Metahohsni and Inheritance 173 



Many birds were killed soon after feeding with Sudan; the time 

 intervening between feeding and killing ranging from one-half 

 hour to days and months. From the examination of these birds 

 it was learned: (i) That the stain may appear in the mesenteric 

 U mphatics within a period of seventy minutes after feeding; (2) at 

 end of two to three hours after heavy feeding a perceptible amount 

 of stain is laid down in the rapidly growing ova; (3) the body fat 

 becomes colored much more slowly than the yolk fat; (4) the sev- 

 eral regions of body fat are not all colored simultaneously, even 

 the subcutaneous fat of some regions remaining colorless at a time 

 when subcutaneous fat elsewhere is quite red. This last fact 

 seems to indicate that there are differences between these 

 several "storehouses" of fat; that some are centers of a most active 

 commerce, there being in these a continuous loading and unloading 

 of wares; whereas there are other storehouses of fat whose portals 

 during normal conditions at least, are quite tightly closed. 



In regard to the conditions under which Sudan is, or can be, 

 deposited, we have determined the following facts: (i) Sudan can 

 be deposited only m growing ov 3.. Indeed, for a perceptible amount 

 of the stain to be taken up the ova must grow more rapidly than 

 do those ova of the fowl which are less than 5 mm. in diameter. 

 (2) Sudan can be deposited with difficulty, and only in small 

 amounts, in a fowl that is not being fed and is thus made to use 

 its store of fat instead of being allowed to grow new fat. These 

 results have been verified on so many birds that there is no doubt 

 of their being entirely reliable. It cannot be said that the starved 

 animals did not get the fat into their circulation because of failure 

 to absorb the stain under the starving conditions, for some of these 

 birds were given the stain by injection, and they too showed just 

 as decidedly the re«=ults sta ted above. One cannot but see in these 

 two results the very strongest evidence that while in the body, 

 Sudan III clings at all times to the fats or their constituent fatty acids, 

 and so goes quite mechanically ivherever these particles go; it is indeed, 

 attached to them. (3) There is moreover in lightly-colored fat 

 a marked tendency of the stain to remain in this fat in the living 

 animal and not to leave it for other contiguous fat. This w^s 

 shown by the sharpness of the inner edges of the bands of stain in 

 the ova, as well as by one's ability to circulate stain through the 



