218 Report or tHe CHEMIST OF THE 
cheese the following compounds: Histidine, lysine, guanidine 
probably, tetramethylenediamine (putrescine) and pentamethy- 
lenediamine (cadaverine). In very few cases do we know any- 
thing of the history of the cheese used in the investigations. 
In our work we are familiar in most cases with the history of 
the cheese, including the conditions of manufacture and of 
ripening. | 
EXPERIMENTAL PART. 
PARANUCLEIN (PSEUDONUCLEIN). 
in the work first done about ten years ago in this laboratory 
in the study of cheese-ripening, a substance was precipitated by 
dilute acids from the water-extract of cheese, showing the gen- 
eral chemical behavior of milk-casein toward different reagents. 
This was called “soluble casein” in the absence of knowledge 
of its specific chemical composition. During the past three 
years we have given more or less attention to the study of this 
substance and, though our work is still incomplete, we present 
here the results obtained up to the present time. 
The fact that the substance in question was precipitated by 
dilute acids, completely by 0.2 per ct. hydrochloric acid, sug- 
gested its resemblance to Chittenden’s so-called casein-dyspep- 
tone.® the insoluble substance obtained in larger or smaller 
quantities when milk-casein is digested with pepsin and hydro- 
chloric acid. 
The substance is obtained from cheese by extraction with 
water and precipitation by hydrochloric acid. We cover about 
3 kilograms of finely ground cheese with water, digest it at 53° 
©. for half an hour and then decant the extract. The residue 
is again covered with water, digested and decanted as before, 
this operation being repeated several times until the extract 
amounts to 4 or 5 liters. After filtration through absorbent 
cotton, the solution is cooled to 10° C. or lower and allowed to 
stand until the fat separates as a solid layer on the surface, 
which can be readily removed. The solution is then heated to 
50° to 55° ©. and treated with enough hydrochloric acid to equal 
0.2 per ct. of the solution. The paranuclein separates as a floc- 
8Studies in Physiol. Chem. Yale Univ., 3: 66 (1887-8). 
