ORGANIC PKINCIPLES. 89 



of the stomach, particularly after commencing putrefaction, 

 cannot be regarded as pure pepsin. It is undoubtedly neces- 

 sary to the digestive action of the gastric juice, which loses 

 its physiological properties when this substance has been 

 coagulated by heat and separated by filtration. Its properties 

 will be more fully considered under the head of digestion, 



Mucosine. 



This is the organic principle of the general secretion 

 of mucous membranes, presenting, however, some differ- 

 ences in different situations. In its general properties it 

 closely resembles albumen ; indeed, what is generally taken 

 as the type of pure albumen, the white of egg, should strictly 

 be called mucosine, as it is the secretion of the mucous mem- 

 brane of the Fallopian tubes, and almost identical with some 

 specimens of pure mucus, such as the secretion at the neck 

 of the uterus during gestation. It is coagulated by heat, 

 strong acids, and the metallic salts. It is formed from the 

 blood by the mucous follicles ;' and, as a small quantity of 

 mucus is discharged from the body, forms one exception to 

 the general law that organic nitrogenized principles are 

 never discharged from the body in health. 



Semi-solid or Solid Principles. 



Most of the liquid elements which we have just considered 

 have been found to be connected, directly or indirectly, with 

 the nutrition of the body. Those which we now have to 

 consider are all directly formed from the organic principles 

 of the blood, and constitute the organic portion of the econ- 

 omy. Here is found to be the final destination of fibrin and al- 

 bumen in nutrition ; for the organic principles constitute the 

 vital elements of all the tissues, and are nourished exclusively 

 by these elements of the blood. We include here the blood 

 corpuscles, which must be regarded as organized bodies, 

 nourished like any of the tissues. The following are the prin- 



