THE PROTEINS. 27 



Add 100 c.c. of saliva to 200 c.c. of 95 per cent alcohol. 



Filter off the precipitated mucin and make the following 

 tests : 



(a) Try some color-reactions for proteins. 



(6) Dissolve some of the precipitate in weak NaOH and 

 then add dilute acetic acid, drop by drop. Note results. 



(c) Boil the remaining precipitate for 10 minutes in a 

 small flask with 50 c.c. of 5 per cent HC1, cool, neutralize 

 with NaOH, and test for a reducing body with Fehling's 

 solution. 



THE NUCLEOPROTEINS AND NUCLEINS. 



As the name indicates, the nucleoproteins originate in 

 and are derived from the so-called mitoplasm or chromatin 

 of the cell nucleus and consequently exist in greater quanti- 

 ties in the glandular organs than elsewhere in the body. 

 Their individual nomenclature is founded upon their place 

 of origin; thus the pancreas, spleen, and yeast nucleopro- 

 tein. By boiling with a weak acid they are decomposed 

 into a protein component and the nucleins which, in turn, 

 upon further boiling, split up into another protein part and 

 the nucleic acids. The nucleoproteins and nucleins only 

 differ, therefore, in the quantity of the protein component 

 which they contain, and since the nucleic acid radical is the 

 carrier of all the phosphorus which is present in the com- 

 pound, it follows that the nucleins are chemically distin- 

 guishable from the nucleoproteins by their larger phosphorus 

 content. The two terms are sometimes used interchangea- 

 bly. The nucleins are acidic in character, soluble in alkalies, 

 but are precipitated by acids and alcohol. Upon treatment 

 with caustic alkalies, nucleic acids result, substances which 

 contain phosphorus in the form of phosphoric acid. The 



