vi THE ANIMAL KINGDOM. 



"Besides the albumen, the gluten, and the starch, other substances, about which 

 this rough method of analysis gives us no information, are contained in the wheat 

 grain. For example, there is woody matter or cellulose, and a certain quantity of sugar 

 and fat." 



Similar substances are found in animals and eggs. " If you break an egg, the con- 

 tents flow out, and are seen to consist of the colorless glairy 'white' and the yellow 

 'yolk.' If the white is collected by itself in water and then heated, it becomes turbid, 

 forming a while solid, very similar to the vegetable albumen, which is called animal 

 albumen. 



"If the yolk i^ beaten up with water, no starch nor cellulose is obtained from it, 

 but there will be plenty of fatty and some saccharine matter, besides substances more 

 or less similar to albumen and gluten. 



" The feathers of the fowl are chiefly composed of horn ; if they are stripped off, 

 and the body is boiled for a long time, the water will be found to contain a quantity 

 of gelatine, which sets into a jelly as it cools, and the body will fall to pieces, the bones 

 and the flesh separating from one another. The bones consist almost entirely of a 

 substance which yields gelatine when it is boiled in water, impregnated with a large 

 quantity of salts of lime, just as the wood of the wheat stem is impregnated with silica. 

 The flesh, on tlie other hand, will contain albumen, and some other substances which 

 are very similar to albumen, termed fibrin and syntonin. 



" In the living bird all these bodies are united with a great quantity of water, or 

 dissolved, or suspended in water ; and it must be remembered that there are sundry 

 other constituents of the fovsd's body and of the egg, which are left uumentioned, as 

 of no present importance. 



"The wheat plant contains neither horn nor gelatine, and the fowl contains neither 

 starch nor cellulose ; but the albumen of the plant is very similar to that of the animal, 

 and the fibrin and syntonin of the animal are bodies closely allied to both albumen 

 and gluten. 



" That there is a close likeness between all these bodies is obvious from the fact 

 that when any of them are strongly heated or allowed to putref}-, it gives off the same 

 sort of disagreeable smell ; and careful chemical an.alysis has shown that they are, in 

 fact, all composed of the elements carbon, hydrogen, oxygen, and nitrogen, combined 

 in very nearly the same proportions. Indeed, charcoal, which is imjiure carbon, might 

 be obtained by strongly heating either a handful of corn or a piece of fowl's flesh in a 

 vessel from which the air is excluded so as to keep the corn or the flesh from burning. 

 And if the vessel were a still, so that the pi-oducts of this destructive distillation, as 

 it is called, could be condensed and collected, we should find water and ammonia in 

 some shape or other in the receiver. Now ammonia is a compound of the elementary 

 bodies nitrogen and hydrogen ; therefore both nitrogen atid hydrogen must have been 

 contained in the bodies from which it is derived. 



"It is certain, then, that very similar nitrogenous compounds form a large part of 

 the bodies of both the wheat plant and the fowl, and these bodies arc called proteids. 



"It is a very remarkable fact that not only are such substances as albumen, gluten, 

 fibrin, and syntonin known exclusively as products of animal and \'egetable bodies, but 

 that every animal and every plant at all jieriods of its existence contains one or 

 other of them, though, in other respects, the composition of living bodies may vary 

 indefinitely. Thus, some plants contain neither starch nor cellulose, while these sub- 

 stances are found in some animals ; while many animals contain no horny matter and no 



