SUGAR, &c. IN THE FOOD. 51 



liest periods of life ; for this food also contains snb- 

 stances, which are not necessary for their support in 

 the adult state. 



The nutrition of the young of carnivora is obvi- 

 ously accomplished by means similar to those by 

 which the graminivora are nourished ; their develope- 

 ment is dependant on the supply of a fluid, which 

 the body of the mother secretes in the shape of 

 milk. 



Milk contains only one nitrogenised constituent, 

 known under the name of caseine ; besides this, its 

 chief ingredients are butter (fat), and sugar of milk. 



The blood of the young animal, its muscular fibre, 

 cellular tissue, nervous matter, and bones, must have 

 derived their origin from the nitrogenised constitu- 

 ent of milk, the caseine ; for butter and sugar of 

 milk contain no nitrogen. 



Now, the analysis of caseine has led to the result, 

 which, after the details given in the last section, can 

 hardly excite surprise, that this substance also is 

 identical in composition with the chief constituents 

 of blood, fibrine and albumen. Nay, more, a com- 

 parison of its properties with those of vegetable ca- 

 seine has shewn that these two substances are iden- 

 tical in all their properties ; insomuch, that certain 

 plants, such as peas, beans, and lentils, are capable 

 of producing the same substance which is formed 

 from the blood of the mother, and employed in 

 yielding the blood of the young animal. (9) 



The young animal, therefore, receives, in the form 



E 2 



