Analysis of Cleavage Products of Mammary Glands. 25 



perimental evidence of the origin of this important constituent of 

 the milk. The theory of Basch that casein is formed by an action 

 of the nucleic acid of the mammary gland upon the protein of the 

 blood plasma has been shown to be untenable by the researches 

 of Mandel and Levene and by Loebisch upon the nucleic acid of 

 the mammary glands. 



In order to determine, if possible, the relationship of the cell 

 substance of the glands to the casein, I prepared the nucleoprotein 

 of the glands according to Hammarsten's method and purified the 

 product by solution in sodium carbonate and reprecipitation with 

 acetic acid several times. The product obtained on purification 

 differed materially as shown below from the same product reported 

 by Odenius and prepared by the same method. 



Odenius. Mandel. 



Nitrogen 17.280 per cent. 15-720 per cent. 



Phosphorus 0.277 " 0-55 1 " 



Sulphur 0.890 " trace 



In order to compare the constitution of this nucleoprotein with 

 casein, the amino acids in several portions were determined by the 

 ordinary methods, after hydrolysis with hydrochloric acid and 

 sulphuric acid and the average results given below obtained. The 

 purine bases and the pyrimidine bases were also determined as 

 given. 





Nucleoprotein. 



Casein. 







0.00 per cent. 



Leucine "1 



8.15 " 



10.50 " 



Valine f 





8.58 



11.00 " 





2.47 « 



4-55 " 







1.50 " 





4.III " 



5.80 " 





.... 3- 021 " 



4.84 » 



Histidine 



3 0 6 4 " 



2.59 » 





1-725 " 







0.930 " 





Thymine 



0.346 " 







0.732 





On comparison with the figures given by Abderhalden and 

 Fischer for the monamino acids and by Hart for the hexon bases 

 we see that there is a striking correspondence in constitution be- 

 tween the casein and the nucleoprotein of the cell substance. 



