igi2] 'Alfred P. Lothrop 169 



duced the same kinds of materials as those that resulted from acid 

 hydrolysis. The "tannin masses" seem to be combinations of 

 tannin and phloroglucin associated with cellulose-like substances. 

 With ferric chlorid, phloroglucin gives a dark blue product but not 

 the blackish precipitate characteristic of the tannin-ferric chlorid 

 reaction. Theref ore, " iron reagents " do not detect tannin in the 

 presence of phloroglucin. 



19. A study of some protein Compounds. Walter H. Eddy. 

 (Published in füll in this issue of the Biochemical Bulletin. )^2 



20. The preparation of thymus histon. Walter H. Eddy. 

 As outlined by Bang, the properties of histon may be summarized as 

 follows : Water-soluble, non-coagulable by heat, precipitated by am- 

 monia in the presence of salts, precipitated from neutral Solution by 

 "alkaloidal reagents," produces precipitates of several soluble pro- 

 teins from their aqueous Solutions. 



The current method of preparing thymus histon, as recom- 

 mended in Standard handbooks such as Abderhalden's and Oppen- 

 heimer's, may be summarized as follows : Extraction of the minced 

 glands with water. Precipitation of the water extract by acid or 

 calcium chlorid, and extraction of this precipitate with 0.8 per cent. 

 hydrochloric acid Solution. Precipitation of the hydrochloric acid 

 extract with ammonium hydroxid Solution, either before or after 

 removing free hydrochloric acid by dialysis. Washing the "am- 

 monia precipitate " free from ammonia with alcohol and ether. 



Kossei, who discovered histon in goose blood, obtained it by 

 saturating the hydrochloric acid extract with sodium chlorid. He 

 alone calls attention to the anomaly noted in our experiments, viz., 

 that treatment with ammonium hydroxid Solution results invariably 

 in the precipitation of a substance that is practically insoluble in 

 water. In a series of many preparations, extending in time over a 

 period of two years and involving materials obtained from many 

 calves, we have come to the conclusion that the " ammonia-pre- 

 cipitation" of a hydrochloric acid Solution of thymus histon results 

 invariably in a water-insoluble product. Furthermore, our 

 experiments show that of two fractions of the same hydrochloric 

 acid Solution, the fraction saturated with sodium chlorid invariably 



^^Eddy: Biochemical Bulletin, 1912, ii, p. 111-22. 



