102 S. HATAI 



earlier observations on the deposition of Sudan III in ova as well 

 as in the soma, but reports also his incidental observations on 

 the growth of the chick fed with Sudan III, as well as those on 

 the question of fat metabolism. In -brief, he finds that Sudan III 

 tends to retard the growth of the chick. He also notices the 

 production of defective feathers among these test chickens. 



Gage ('08) repeated Riddle's experiment and found that while 

 Sudan III is deposited in the hen's egg, it does not appear in 

 new-born albino rats whose mother has been fed with this dye- 

 stuff for some days previously. Gage thinks that the placenta 

 prevents the entrance, of Sudan III into the fetal circulation. 



In 1912 Mendel and Daniels published their extensive observa- 

 tions on fat metabolism, using not only Sudan III, but several 

 other fat-soluble dyestuffs. These investigators touch on nu- 

 merous interesting problems regarding the fate of the dyes after 

 these are taken into the animal body, and I shall later on refer 

 to this important paper. 



Another study was made by Corper ('12), who fed guinea-pigs 

 with several dyestuffs which are soluble in fat, including Sudan 

 III, with a view to studying the biochemistry and chemo- 

 therapy of tuberculosis. Corper fed the animal with a rather 

 large dose (0.025 grams per diem) of Sudan III for long periods 

 (over 200 days) without apparently producing any ill effects. 



While I was feeding Sudan III to young albino rats to deter- 

 mine whether it appeared in the newly formed myelin sheaths, I 

 noted that the rats which were receiving a small amount (about 

 8 to 9 milligrams per diem) of Sudan III mixed in olive oil, not 

 only failed to grow, but appeared in many respects strikingly 

 abnormal. 



Preliminary examination of the organs revealed the fact that 

 most of these organs were distinctly altered in appearance. The 

 most noticeable alteration was the complete atrophy of the 

 thymus in every one of these seven test rats. Inasmuch as these 

 alterations were not recordefi by previous investigators, and par- 

 ticularly because of the behavior of the thymus towards Sudan 

 III, the present investigation was undertaken. 



