43 S Histon and its Preparation [April 



calcium chlorid and comes down as calciuni-nucleinate. In our 

 analyses we were unable to detect even a trace of calcium in the 

 ash. It is possible, of course, that a nucleic acid fraction was sepa- 

 rated from the histon product by the acid treatment, which, in the 

 presence of other protein, may have formed a protein-nucleate pre- 

 cipitable by calcium chlorid. It might be true therefore, as Bang 

 (6) Claims, that histon exists in the cell as a histon-nucleate. The 

 failure to obtain any nucleic acid in these tests, and the different 

 nitrogen figures for the product precipitated with calcium chlorid, 

 together with the agreement between the values for nitrogen con- 

 tent of the nucleoprotein and those obtained by both Bang and 

 Huiskamp, suggest that histon occurs in cells as a true nucleo- 

 histon and not as a nucleate. 



VI. SUMMARY OF CONCLUSIONS 



These studies seem to show that histon obtained from aqueous 

 extract of thymus gland by precipitation with ammonia is essentially 

 dififerent from histon obtained by Saturation with sodium chlorid. 

 The histon precipitated by ammonia is insoluble in water and has a 

 higher nitrogen content than the histon precipitated with sodium 

 chlorid. The latter product is readily soluble in water, even after 

 drying at 105° C, and contains an appreciable amount of chlorin in 

 combined form. The difference relates apparently both to the con- 

 tent of chlorin and to the presence of a protein fraction in the salt- 

 precipitated histon which is absent from that obtained with ammonia. 



The preliminaiy use of alcohol to precipitate histon and other 

 protein materials in the glands seems to offer marked advantages 

 over the direct water-extraction method, both in öbviating putre- 

 faction and in facilitating filtration of the aqueous extract. 



Bang's contention that ammonia does not precipitate histon in 

 the absence of salts is incorrect. It is true, however, that their pres- 

 ence facilitates the process. 



The data pertaining to the residues insoluble in 0.8 per cent. 

 hydrochloric acid Solution seem to confirm Huiskamp's views rather 

 than those of Bang, but in view of the power of nucleic acid to 

 combine with protein and the absence of calcium from the ash of 

 the calcium chlorid-precipitated fraction, the matter cannot be 

 regarded as settled. 



