VEGETABLE ALBUMEN. 389 



of sulphur, and phosphorus. Its exact composition is 

 given in the Appendix. It is a grey substance, and is 

 the material which gives its cohesion to bread. 



975. VEGETABLE ALBUMEN AND CASEIN. 



What is said . -i r. 



of vegetable Vegetable albumen is a similar substance, 



contained, ni smaller quantity, in the juices 

 of fruits and vegetables. It is coagulated 

 by heat, like the white of egg, when the juices are 

 boiled. Vegetable casein is another substance of very 

 similar composition and properties, found principally 

 in the seeds of leguminous plants. It precipitates like 

 the curd in sour milk, when a little acid is added to 

 an aqueous extract of the seeds. These substances 

 derive their names from their resemblance to animal 

 fibrin, albumen, and casein. Vegetable casein is also 

 called legumine. All of these substances were at one 

 time supposed to be compounds of a single substance, 

 called protein, itself free from both sulphur and phos- 

 phorus. Later experimenters have not succeeded in 

 isolating such a substance, and the theory is therefore 

 abandoned. The name is retained in this work as a 

 convenient designation of the class of substances here 

 considered. 



976. OCCURRENCE. One or more of 



Where are the 



above subxtan- these substances is present in greater or 

 cesfuund? legs quant i t y in a u parts o f p i ants . They 



are found accumulated with starch, in the fruit and 

 seed. The seeds of cereals, such as wheat and rye, 

 and those of leguminous plants, such as peas and beans, 

 contain them in large proportion. 



