Animal jelly affords a sufficiently nutritious aliment, of easy digestion when properly prepared, and less stimu lant and septic than substances abounding in the other principles. Hartshorn and calves' feet jelly have ac cordingly long been regarded as food extremely well adapted to the feeble powers of the sick and convales cent.
.41bumen is, like gelatine, soluble in water ; but it is distinguished by its coagulation on the application of heat, and its consequent separation from the water in which it had been dissolved or diffused. It is more animalized than gelatine, but less so than fibrins. The white of an egg presents us with the best and most familiar example of albumen. It exists in the serum of blood, and the curd of milk has nearly the same pro perties. Coagulated albumen, according to Mr Hatchet's experiments-, forms a)so a principal part of the cartila ges, membranes, hoofs, horns, feathers, quills, and hairs of animals.
As an aliment, albumen is highly nutritive ; but ex cepting as it exists in the white of the egg, is not used as a separate article of diet, or uneonibined with the other principles.
Fibrine exists in a dissolved state in the circulating blood, and spontaneously coagulates when allowed to rest. It constitutes also the fibrous part of the muscu lar flesh. It may be exhibited by washing the coagulum of blood, or a portion of any muscle, until they become colourless. Fibrine, or animal gluten, is a white, tough, elastic, fibrous substance, insoluble in water, and con taining in its composition a greater quantity of nitrogen than any of the other principles. Though in a separate and uncombincd state, it is not employed as aliment, fibrine is largely consumed with the flesh of animals. It is excluded from soups and broths, which necessarily contain only the soluble principles of the flesh. Fibrine„ however, is readily dissolved by the gastric fluid, and may be regarded as the strongest and most stimulant of aliments.
.4ninzal oil, or fUt, is too well known to require any particular description in this place. It is a nutritious component part of animal substances, but not so easily digested by ordinary stomachs as the other alimentary principles. The most robust only are capable of over coming a full meal of fat. The stomach is oppressed
by it, and nausea, rancid eructations, and general dis order, are not uncommonly produced. More sparingly eaten, however, and with a due proportion of the flesh, it agrees well with most people, and is justly regarded as highly nourishing.
The different parts of animals employed as aliments come next to be considered. They may be distinguish ed into fluids and solids. The only fluids which can be regarded as alimentary, are the blood and the milk of animals.
The blood is composed of the three alimentary prin ciples, fihrine, albumen, and gelatine ; it contains be sides water, the red globules, and sonic saline matters. We should therefore conclude the blood to be very nu tritive. It is, however, generally esteemed a heavy and indigestible aliment in whatever way prepared. It must, however, be largely consumed in every flesh meal ; and the blood of some animals, as that of the hog and ox, is made into puddings by the country people, and highly relished by them. This kind of food, however, says Lieutaud, requires all the powers of the most robust stomachs.
Milk is the fluid secreted by the females of the mam malia class for the nourishment of their young. The principles contained in it are oil, albuminous and sac charine matter, water, and some saline matters. Milk is almost the only animal product susceptible of the vinous and acetous fermentations ; and in this particu lar it seems to approximate to the nature of vegetable substances. Indeed the sugar on which this property seems to depend, is to be considered rather as a vegeta ble than animal principle. And thus milk, containing at once animal and vegetable principles, is a sort of mixed aliment.
Woman's milk, the food pointed out by nature as the best adapted to the young of our own species, contains less curd, but more oil, and more sugar than cow's milk. The ass and the mare yield milk which resembles that of the woman, in containing larger proportions of the oily and saccharine, than or the cascous matter, which most abounds in the inilk of the cow, goat, and sheep Of the constituent parts of milk, the albuminous is tIn• most annualised ; the saccharine is more properly a vegetable principle, and the oily may be regarded as intermediate.