I9I3] Wolter H. Eddy 435 



The clear filtrate from the resultant precipitate, after acidification 

 with nitric acid, gave a good chlorin test with silver nitrate. It 

 therefore seems correct to assume that ammonia actually separates 

 chlorin from the sodium chlorid-precipitated siibstance and that 

 chlorin is present in the latter histon product in an adsorbed or com- 

 bined condition, not as an impurity. 



A further investigation of the validity of these conclusions is 

 in progress. 



F. Conclusions. The results of this vvork justify the follow- 

 ing conclusions: Both sodium chlorid and ammonia precipitate, 

 from histon-hydrochlorid Solutions, products having characteristic 

 histon properties but differing in water-solubility, and in nitrogen 

 and chlorin contents. The filtrates from both the ammonia- and 

 sodium chlorid-precipitates give strong biuret reactions and are 

 precipitable by alcohol-ether and Saturation with ammonium sulfate. 



The latter precipitates are not identical in properties and, while 

 parahiston is possibly admixed with them, they also contain frac- 

 tions of other protein matter which makes them different from 

 para-histon and from one another. At present the nature of this 

 protein admixture, and hence the exact nature of the difference 

 between sodium chlorid- and ammonia-precipitated histons, is still 

 uncc. vain. 



2. An improvement in the method o£ preparing thymus 

 histon. In following out the various methods of preparing the 

 hydrochlorid Solution of thymus histon it was difficult to obtain a 

 water extract of the glands which would filter clear. The glands 

 are also particularly prone to putrefaction at the beginning of the 

 extraction process. The latter difficulty Avas overcome by conducting 

 the extractions in a refrigerator rather than by depending upon the 

 use of preserv'atives such as Chloroform and toluene. Both difh- 

 culties can however be avoided by the following modified method 

 which is recommended as more practical than any of those out- 

 lined in the general literature. 



After freeing the glands from fat with a knife, pass them 

 through an ordinary meat grinder and pour the hash directly into a 

 comparatively large volume of 95 per cent. alcohol. All the protein 

 material is precipitated and all chance of putrefaction is thus 



