428 Histon and its Preparation 



TABLE 5 



Data pertaining to the responses of histons to protein color tests 



[April 



6. A summary of characteristic properties of histon (2). 

 Histons are precipitated from aqueous Solutions by ammonia, and 

 are insoluble in excess of the reagent. Bang (2) claims that the 

 presence of salt is necessary for complete precipitation. Huiskamp 

 (10) Claims that the presence of salt hinders the ammonia-precipita- 

 tion of thymus histon. 



Histons are coagulated by boiling only in the presence of salts. 

 This coagulum is soluble in dilute hydrochloric acid. The protein 

 is not reprecipitated when the acid Solution is neutralized. 



Histons are precipitated by concentrated nitric acid Solution in 

 the cold. The precipitate dissolves on heating and reappears on 

 cooling. 



Histons are precipitated by the "alkaloidal reagents" from 

 neutral or weakly alkaline Solutions. 



Neutral Solutions of histon yield precipitates with neutral Solu- 

 tions of egg albumin and with blood serum ; also with such Solutions 

 of caseinogen and serum albumin, if these are poor in salts. 



IV. THYMUS HISTON 



I. The nature of the histon complex. The most exhaustive 

 studies of histon developed from a discussion of the form in which 

 histon occurs in the tissues. Most of the investigation in this con- 

 nection dealt with thymus histon. The researches of Malengrau 

 (20), Lilienfeld (19), Huiskamp (10, 11), and Bang (3, 4, 5, 6), 



* P = positive ; N = negative. 



