108 



MANUAL OF PHYSIOLOGY. 



Vegetable Food. Vegetables differ from animal food : 



(1) In containing a much greater proportion of material which 

 for man is indigestible (cellulose), and a less proportion of real 

 nutritive material. 



(2) The percentage of proteid is below that of animal food, 

 and the proportion of carbohydrates is generally much greater, 

 while the amount of fat is small but varies considerably. In order, 

 therefore, to get the required amount of nutritive material from a 

 purely vegetable diet, it is necessary to consume a much greater 

 quantity, and the amount of excrement indicating the indigesti- 

 ble matters is proportionately increased. 



FIG. 44. 



Section of Pea, showing starch and aleurone granules imbedded in the protoplasm of 

 the cells. (After Sachs.) a. Aleurone granules, st. Starch granules, i. Intercellular 

 spaces. 



Cereals. The most valuable forms of vegetable food are those 

 obtained from the seeds of certain kindred plants (Graminacece). 

 wheat, rye, maize, oats, rice, etc., which when ground are used 

 either as " whole meal," or, the integument (" bran ") being 

 removed, as flour. They contain different kinds of proteid. (1) 

 A native albumin soluble in water and coagulable by heat, and in 

 many respects like animal albumin ; but as it cannot be obtained 

 pure it is imperfectly known. (2) Vegetable fibrin, an elastic 

 body which coagulates spontaneously and is difficult to separate. 

 (3) Vegetable glue or gliadin, which gives the peculiar adhe- 

 siveness to the gluten, as the proteid mixture obtainable from 



