NITROGENIZED ALIMENTARY PRINCIPLES. 179 



of one animal may be used for the nourishment of another, the flesh of an animal thus 

 nourished is not an appropriate food for man. We should live upon vegetable principles 

 taking them in part directly, and in part indirectly, or after they have been prepared and 

 assimilated by animals. As a rule, the nutritive principles in vegetables are relatively 

 less abundant than in animal food, and the indigestible residue is therefore greater; but 

 man, and even the carnivorous animals, may be nourished for an indefinite period by ap- 

 propriate articles derived from the vegetable kingdom. 



Vegetable Fibrin and Caseine. Many of the vegetable juices contain a spontaneously- 

 coagulable substance which has been called vegetable fibrin. This is particularly abun- 

 dant in the cereals. What has been said concerning fibrin as an alimentary principle is 

 applicable to this substance. Its proportion in vegetables is small, unless we consider as 

 vegetable fibrin, gluten, one of the most abundant and important of the nutritive principles 

 contained in ordinary flour. 



A principle may be extracted from beans, peas, and other vegetables of this class, 

 which is thought by many to be identical, in all respects, with caseine and has been 

 called vegetable caseine. The article called tao-foo, made by the Chinese from peas, is 

 apparently identical with cheese. The peas are reduced to a pulp by boiling and the 

 vegetable caseine is coagulated by rennet,being afterward treated in the same way as the 

 analogous substance manufactured from milk. Vegetable and animal caseine have, as far 

 as we know, identical physiological relations. Vegetable caseine is sometimes called 

 leguinine. It is sparingly soluble in water, is insoluble in alcohol, is not coagulated by 

 heat, and is precipitated by the mineral acids and some of the mercurial and calcareous 

 salts. It is dissolved by the vegetable acids. 



Another substance, supposed by some to be identical with vegetable caseine, is aman- 

 dine. This is found widely distributed in the vegetable kingdom, but it hardly presents 

 points of distinction from leguinine, sufficient to mark it as a distinct principle. 



Gluten. In many of the vegetable grains known as cereals, there exists, in variable 

 proportions, a highly-nutritive nitrogenized substance called gluten. This is found in 

 great abundance (from ten to thirty-five per cent.) in wheat. Its proportion in other 

 grains is insignificant. It may be easily extracted from ordinary wheaten flour, by knead- 

 ing under a stream of water, when the starch, a little sugar, vegetable albumen, mucilage, 

 and some soluble matters are removed, and the gluten remains in the form of an adhesive, 

 elastic, grayish -white mass. Gluten is capable of acting as a ferment, transforming starch 

 first into dextrine and then into sugar. It is the substance which gives the peculiar con- 

 sistence and porous character to bread. 



The nutritive power of gluten is so great, and it contains such a variety of alimentary 

 principles, that dogs are well nourished and can live indefinitely on it when taken as the 

 sole article of food. This experiment was actually made by the gelatine committee ; and 

 the fact will be easily understood when we consider that it is a compound of no less 

 than three distinct nitrogenized principles, together with fatty and inorganic matters. 

 In one of the methods of treatment of diabetes mellitus, in which all saccharine and 

 amylaceous matters are excluded from the food, it has been found difficult to nourish the 

 body sufficiently and give proper variety to the diet without bread ; and, under these 

 circumstances, the use of bread composed almost exclusively of gluten has been highly 

 successful. With proper care, a bread can be made in this way, which is eminently 

 nutritive and not unpalatable. 



Gluten obtained by washing flour under a stream of water contains vegetable fibrin, 

 vegetable albumen, and a substance soluble in alcohol, called glutine. This latter sub- 

 stance is found in quantity only in wheaten flour. 



In the different articles of food belonging to the vegetable kingdom, there are un- 

 doubtedly many nitrogenized matters with the distinguishing properties of which we 



