116 S. HATAI 



It appears to me, on the other hand, that in the test rats the 

 normal metabohsm of fat must have been much disturbed, as can 

 be seen from the presence of a large quantity of fat both in the 

 liver and blood, and thus we may consider that the stained fat 

 also is less readily utilized. 



Another interesting question is the origin of the lipoids con- 

 tained in the organs. We found that Sudan III is practically 

 absent, even after five weeks of continuous feeding, in nearly 

 all the organs so far examined. Particular interest attaches to 

 its absence from the brain in which nearly 50 per cent of the solids 

 are repreisented by lipoids. Moreover, the amount of Sudan III 

 to be recovered from the liver, pancreas, lungs, and kidneys is 

 almost negligible. Microscopical examination fails completely 

 to reveal any trace of Sudan III or stained fat in the organs 

 even when the extraction mass yields a trace of it. Since Sudan 

 III is so intimately combined in fat, and wherever fat appears 

 Sudan III is always found, and furthermore since Sudan III 

 stains not only fat or oils, but fatty acids also, it seems prob- 

 able that if the cell elements should absorb the fat or fatty acids 

 for building up the organ lipoids, we might expect Sudan III to 

 be absorbed also. There is no a priori reason to suppose that 

 Sudan III alone is rejected, w^hile the fat or fatty acids containing 

 it are capable of being absorbed. 



This result suggests that the lipoids found in the organs may 

 not be formed by the fat or fatty acids furnished from without, 

 but are elaborated by the organ itself; in other words, the organ 

 lipoids are endogenous and not exogenous in origin. 



CONCLUSIONS 



1 . Albino rats 27 to 33 days old were fed with Sudan III mixed 

 in olive oil. ' The amount of Sudan III given daily was about 

 8 or 9 milligrams in one series and 10 to 15 milligrams in the 

 other. A dose of 20 milligrams was found to be too large. 



2. In all cases Sudan III retards to a considerable extent the 

 normal rate of the body growth. Olive oil alone as given by me 

 does not produce this effect. 



