ORGANS AND FUNCTIONS OF DIGESTION IN ANIMALS. 571 



ounces of bread, and four ounces and a half of lentils ; they are not 

 much more nutritious than the succulent vegetables, but, like these and 

 fruits, they contain, which bread does not, potash, so essential to the 

 muscles ; hence, perhaps, their utility in preventing and curing scurvy. 



A well-selected vegetarian diet is quite equal to the maintenance of 

 life and health ; the Japanese, the Hindoos, and the lazzaroni of 

 Naples, subsist chiefly on a vegetable diet. The macaronis and ver- 

 micellis are composed of gluten, with but a small proportion of starch. 

 Indian corn, and also wheat, though not in such quantity, contain 

 cerebric acid, a remarkable nitrogenous compound, found in the nervous 

 substance, of very high atomic constitution. Broth is a very weak 

 nutriment, even when some strong farinaceous element is added to 

 it ; so is beef-tea, if properly prepared. Meat contains principles 

 which may be extracted, some better by cold water, others by warm 

 water, and others, again, by boiling ; it should, therefore, be cut into 

 small pieces, be submitted for three hours each time, in succession, to 

 half its weight of cold, of warm, and of boiling water; the fluids, 

 strained off from the first and second macerations, are to be mixed 

 with that strained off hot from the third or boiling process, and the 

 mixture should be just brought to a boiling heat to cook it; the 

 fat should be skimmed off; a few drops of some acid, with salt, will 

 increase the flavor. Thus prepared, beef-tea contains albumen, traces 

 of syntonin, fibrin, cruorin, and myochrome, in a flocculent state ; and 

 gelatin, creatin, cerebric acid, perhaps glycogen, inosite, paralactic, 

 lactic, and inosinic acids, and salts of potash, soda, and magnesia, in a 

 state of solution ; nearly all the syntonin remains in the shrunken meat ; 

 the fat is never absolutely removed. Beef-tea, if good, is a light, 

 nutritious, easily assimilated, conservative, and stimulating food. The 

 now much used extractum carnis or extract of meat, is the inspissated 

 juice of meat, and resembles a viscid beef-tea ; but it contains no gela- 

 tin, and no glycogen or sugar ; to be truly nourishing, it requires the 

 addition of some albuminoid and amylaceous materials. Malt liquors 

 are more nutritious than weak beef-tea. Alcohol stimulates and devel- 

 ops heat ; it seems to be partly digested and oxidized, though a great 

 portion escapes unchanged by the lungs, skin, and kidneys. 



THE ORGANS AND FUNCTION OF DIGESTION IN ANIMALS. 



The process of digestion, by which food is dissolved and rendered absorb- 

 able by the living body, is almost universally performed by animals ; and a 

 digestive apparatus is found in nearly all animals, a few Entozoa and most 

 Protozoa excepted. 



The general idea of such an apparatus, is an internal digestive cavity, com- 

 municating with the exterior. The plan of construction of this internal re- 

 ceptacle, presents a general resemblance in each separate Subkingdom, but in 

 each, it offers further modifications. These are the most varied and detailed in 

 the Vertebrata, but they exist also in the Mollusca and Annulosa, and may 

 be traced in the Molluscoida, Annuloida, and even in the Ccelenterata. In 

 the Vertebrata, the plan is not only modified in each Class, but, in the Mam- 

 malia especially, it presents peculiar adaptations, suiting it to the carnivor- 

 ous, insectivorous, frugivorous, herbivorous, omnivorous, and marine habits 

 of the animals composing its several Orders. The digestive apparatus be- 

 comes, indeed, like the rest of the economy, more complex as we ascend in the 



