96 SECRETION. 



has also found that the mucous membrane of .the stomach 

 of an infant a few days old, that had recently died, coagu- 

 lated woman's milk more readily than the mucous membrane 

 of the stomach of the calf. 1 



Non-Nitrogenized Constituents of Milk. Non-nitro- 

 genized matters exist in abundance in the milk. The 

 liquid caseine and the water hold the fats, as we have 

 seen, in the condition of a fine and permanent emulsion. 

 This fat has been separated from the milk and analyzed by 

 chemists, and is known under the name of butter. In 

 human milk, the butter is much softer than in the milk of 

 many of the inferior animals, particularly the cow ; but it is 

 composed of essentially the same constituents, though in 

 different proportions. In different animals there are de- 

 veloped, even after the discharge of the milk, certain odor- 

 ous principles, more or less characteristic of the animal 

 from which the butter is taken. 



The greatest part of the butter consists of margarine. 

 It contains, in addition, oleine, with a small quantity of 

 peculiar fats, not very well determined, called butyrine, 

 caprine, caproine, and capriline. The margarine and 

 oleine are principles found in the fat throughout the body ; 

 but the last-named substances are peculiar to the milk. 

 These are especially liable to acidification, and the acids 

 resulting from their decomposition give the peculiar odor 

 and flavor to rancid butter. 3 Bromeis estimated the differ- 

 ent constituents of the butter from cow's milk, and found it 

 to contain sixty-eight parts of margarine, thirty parts of 

 oleine, and two parts of butyrine, capronine, and caprine. 3 



1 SIMON, Animal Chemistry with Reference to the Physiology and Pathology of 

 Han, Philadelphia, 1846, p. 333. 



2 Butyrine was discovered, and the changes which it is liable to undergo 

 were first described by Chevreul. (Faite pour servir d Vhistoire du beurre de 

 vache. Extraits d'un memoire lu d VAcademie des Sciences, le 14 juin, 1819. 

 Annales de chimie et de physique, Paris, 1823, tome xxii., p. 373.) 



8 BROMEIS, Ueber die in der Butter enthaltenen Fette und fetten Sauren. An~ 



