VEGETABLE CONSTITUENTS OF BLOOD. 



Casein, or cheese, the principal ingredient of milk, must alao 

 be enumerated as a material used in the formation of blood. 

 Casein is generated in the animal economy, and is the only azo*. 

 tised nutriment furnished by the mother to the young animal. 



Now albumen, fibrin, and casein contain sulphur, a circum- 

 stance by which they are distinguished from all other component 

 parts of the animal body. This sulphur does not exist in the 

 form of an oxide, such as sulphuric acid or one of its salts. It 

 is well known that the albumen of eggs emits, during its putre- 

 faction, sulphuretted hydrogen gas ; and it is owing to this that 

 rotten eggs possess the property of blackening silver or other 

 metals with which they may be brought in contact. During the 

 putrefaction of fibrin and albumen, the same gas is likewise gene- 

 rated. There are many other ways by which we might prove 

 the presence of sulphur in these bodies. 



From what source does the animal body derive these three fun- 

 damental components ? Unquestionably they are obtained from 

 the plants upon which the animals subsist : but in what form, and 

 in what condition, are they contained in plants ? 



Recent investigations of chemists have enabled us to answer 

 these questions with positive certainty. Plants contain, either 

 deposited in their roots or seeds, or dissolved in their juices, 

 variable quantities of compounds containing sulphur. In these 

 nitrogen is an invariable constituent. Two of the compounds 

 containing sulphur exist in the seeds of cereal plants, and in 

 those of leguminous vegetables, such as peas, lentils, and beans. 

 A third is always present in the juices of all plants; and it is 

 found in the greatest abundance in the juices of those which we 

 use for the purpose of the table. 



A very exact inquiry into the properties and composition of 

 substances has produced a very remarkable result, namely, that 

 the sulphur compound dissolved in the juice of plants is, in re- 

 ality, identical with the albumen contained in the serum of 

 blood, and in the white of an egg ; that the sulphur compound in 

 the seeds of the cereals possesses the same properties and com- 

 position as the fibrin of blood ; and that the nutritious constitu- 

 ent of peas, beans, ard lentils, is actually of the same nature and 

 composition as the casein of milk. Hence it follows that plants, 



