COMPOSITION OF MILK. 21 



stance named fibrin. This seems to be similar to the nuclein 

 mentioned by Fleischmann, if not the same. But as these 

 substances are present to a very small extent, citric acid, urea, 

 and fibrin being present to the extent of .12, .007, and .0002% 

 respectively (Fleischmann and Babcock), they are of little 

 importance. 



