1913] Walter H. Eddy 423 



cipitating with alcohol-ether. Preparation II. {Levene method). 

 After transformation to picrate, and removal of picric acid with 

 sulfuric acid as detailed above, the histon was precipitated from the 

 sulfuric acid Solution with ammonia. The filtrate containing the 

 para-histon was then precipitated with alcohol, the precipitate puri- 

 fied by Solution in hot water, and reprecipitation with alcohol-ether. 

 The product was then dried to constant weight. Fleroff determined 

 the properties of his material in studies of the alcohol precipitate 

 and its water-solution. 



H. Gadus histon: Kossel and Kutscher, 1900 (16). Dry 

 codfish sperm was extracted many times with hydrochloric acid 

 (20 c.c. conc. hydrochloric acid Solution to each liter of water), 

 the combined acid Solutions then filtered, histon precipitated by 

 Saturation with sodium chlorid, and purified by dialyzing against 

 running water until free from sodium chlorid and a clear water- 

 solution obtained, which was then precipitated with ammonia, and 

 the histon washed with ammonia-water, alcohol, and ether, and 

 dried to constant weight, 



I. LoTA histon: Ehrström, 1901 (8). Dry sperm of the 

 burbot was extracted with conc. hydrochloric acid Solution at room 

 temperature for an hour, the acid extract treated with 3-4 volumes 

 of water, the filtrate neutralized with sodium hydroxid and diluted 

 with five volumes of water to precipitate the histon. This product 

 was purified by digesting the precipitate on a water bath with 0.5 

 per Cent, hydrochloric acid Solution, precipitating the histon with 

 ammonia, washing the material with water, alcohol, ether, and 

 drying to constant weight. Ehrström used a hydrochloric acid 

 Solution neutralized with sodium hydroxid for the determination of 

 properties. His analyses were based on the ammonia-precipitated 

 product. 



J. Hen blood histon: Ackerman, 1904 (i). {Plenge's 

 method). The hen blood was centrifuged with 0.9 per cent. sodium 

 chlorid Solution for the Isolation of the corpuscles, which were 

 extracted with alcohol for the removal of pigment and again centri- 

 fuged free from alcohol, and dried with alcohol and ether. Histon 

 was obtained by extracting the dry material with i per cent. hydro- 

 chloric acid Solution, precipitating with ammonia, and purifying by 



