unknown important purposes; the introduction of certain salts into the blood may be suggested. The facts published by Dr. Baly of the occurrence of scurvy in public institutions, where the diet is defective in vegetable acids, and the immediate cessation of that disease when vegetables containing organic acids are given, as potatoes, seem to confirm this opinion. The propriety of separating the gelatinous from the proteinaceous principle is obvious; and as to the saline substances, there is as much reason to regard the chloride of sodium, and probably phosphate of lime, as also iron in some of its combinations, in the light of distinct alimentary principles, as any other combination of the elements of matter employed as food.

The reasoning employed in this volume does not convince us that alcohol in any of its forms of mixture, ought to be regarded as an alimentary principle. This class of substances should surely be limited, at least, to combinations of the elements of matter, which are necessary or wholesome to be presented to the digestive organs, (for the purposes whether of nutrition. or respiration,) in the physiological or healthy state of the animal economy; and under ordinary circumstances. Admitting the facts cited by Dr. Pereira, they prove at most, in our minds, that alcoholic compounds, when judiciously resorted to, are excellent remedial agents, and may be employed with advantage to counteract the effects of certain abnormal states into which the constitution of man is liable to be precipitated; be it by his follies or by virtue of his enterprising nature. Seeing no reason to doubt the rationale of its operation, adopted from Liebig; or that it serves to warm the system, when this is exposed to undue causes of depression of temperature; or to excite the organic functions, when they have become excessively depressed; such effects must be held to be therapeutical rather than dietetical; and although, in consequence of the very general employment of alcohol by civilized man, it is important to treat of it in a work on food and on precepts of diet, it cannot be proper to rank it as an approved constituent of ordinary wholesome alimentation. The controversy at present raging as to the source of the fat of animals, whether introduced from without, or formed within the system, has an important bearing on the general subject of assimilation, primary and secondary. Liebig, comparing the quantity of fat deposited with the quantity of the oleaginous principle contained in the food, came to the conclusion that fat must be formed in the body by the abstraction of oxygen from starch, sugar, and other non-azotized food. Dumas, Payen, and Boussingault afterwards proved that the food employed in the experiment, contained much more oily matter than Liebig was aware of— that maize, instead of containing very little, has from four to nine per cent.; rendering it in some degree probable that all the fat of the animal was derived ready formed from the food. There are many most interesting facts in favour of Liebig's view; thus, bees being fed with honey alone, quite free from wax, one part of wax was produced for every twenty parts of honey consumed. The analogy between wax and oil, and the near identity of honey and sugar, seem to indicate that oily and waxy substances are formed in the economy from food. In a recent analysis, Dr. G. O. Rees found a large quantity of oil in the chyle of a donkey, first kept for many hours without food and then fed with beans; but beans are said to contain no oil, and the lymph of the animal at the same time furnished a much smaller proportion of oil than the chyle.

Since this controversy commenced, Peleuze appears to have discovered that on submitting sugar to a slow fermentation, under circumstances as nearly as possible analogous to animal digestion, the formation of butyric acid, that is to say, of one of the constituents of animal fats, takes place. This is one of the questions, upon the settlement of which our knowledge of the real digestive powers of the higher orders of animals in a great measure depends. Are Liebig and Dumas both right?-the fatty matter being usually derived from that which preexists in the food, and the system having the power of elaborating it from saccharine compounds when the supply from the former source is deficient.

A most striking circumstance connected with these alimentary prin ciples-that no one of them, in its isolated state, is capable of affording nourishment to animals for any length of time, calls for remark in this place. They all excite aversion after they have been used for a very short time. Gluten is the only compound, belonging in anywise to this class of substances, which has been found to be consistent with prolonged nutrition. The glutinous part of wheat was first discovered early in the last century by Beccaria, who, with Rouelle, proved that to it wheaten flour and some other vegetable substances owe their superiority as human food. According to a table given by Dr. Pereira, the proportion of glutinous matter contained in different varieties of wheat, varies from 9.2 to 35.1 per cent. Now this "Beccaria's gluten" is a mixture of several organic principles. By boiling in alcohol it may be resolved into an insoluble portion, being vegetable fibrin, and a soluble part, consisting probably of at least two substances, mucin and glutin; and, as remarked by Magendie, this substance, containing much gluten (v. fibrin),"combined with a little albumen, gum, mucilage, fecula, and even sugar," is really a very compound substance. Hence its sufficiency for the nourishment of animals. A consideration of these facts leads to the conclusion, that protein and its compounds undergo some important changes in the digestive organs, to prepare them for secondary assimilation, and that they require to be mixed or combined with other substances in order to ensure the due progression of these changes.

The above remarks are in no way intended as a censure of Dr. Pereira's labours. They are made rather in exemplification of the imperfect state of dietetics as a science, and in anticipation of those improvements which may be hoped for in the third part of the organic chemistry, promised to the public by Professor Liebig.

III. COMPOUND ALIMENTS. The third and last chapter of the first part of the work before us treats of the different varieties of food as it is furnished by the markets for our tables. These consist of animal and vegetable substances in their prepared or unprepared state, every individual of which contains two or more, and sometimes many, of the alimentary principles already described. Food has been regarded, in this point of view more especially, in preceding treatises on the subject, and Dr. Pereira's work differs from others, in the chemical and dietetical properties of the alimentary principles as well as of the elements being made essential parts of this branch of medical study. We shall here have to notice Dr. Davidson's and also Dr. Truman's productions, although both the one and the other must be looked upon rather as intended for the general than the scientific or medical reader. They will be found, however,

to contain numerous interesting facts, and in some respects they supply what may possibly be regarded as omissions in the one at the head of our list, which we have chosen as a text.

That the particular kinds of food employed by different nations, and in various climates and regions of the earth, is the result of accident, necessity, and conventional usage, rather than a selection made upon rational principles, must be sufficiently obvious. In fact, no such thing as principles in dietetics could be known or surmised by man in his primitive state, and very few have been discovered in the various stages of his advance towards civilization. Still, as in other branches of hygiene and medicine, experience-although very frequently deceptive-has for the most part proved herself a faithful guide, and we deem it advantageous to be made acquainted with the customs of different nations as respects the sustenance of their bodies. In these times also, when food for the multitude is too certainly a pressing want, it behoves us to consider all possible sources thereof, and the dietetical value of every available natural production. "Quæ in terris gignuntur omnia ad usum hominum creantur," and as animals exercise their instinct in obtaining food, so man must bring his reason to determine the problem of providing aliment for multiplying generations.

We find it noticed by Dr. Truman that horse-flesh is not an uncommon article of diet in Denmark and Sweden, and a large quantity is consumed as food in Paris. The Tartars, Arabs, and Patagonians eat asses. Dogs were formerly much employed as food in Europe; they are also eaten by the Chinese, and by some savage nations, and even in civilized Paris;evidence is in fact adduced that dog's flesh is sweet and wholesome meat. Elephants are considered delicacies in Cochin China; camel's flesh in Egypt; and in China, again, rats and moles are sold by weight in the markets, for food. Whales, walruses, seals, bears, beavers, otters, badgers, foxes, &c., are eaten by the inhabitants on the coasts of the polar seas; and the Caffres consume lions. So also, many birds and their eggs, which are foreign to our notions as articles of diet, are employed as such in different countries; and the same may be affirmed of crocodiles and various reptiles and serpents; of white ants, caterpillars, centipedes, snails, earthworms, and even human flesh. Among vegetables, chestnuts are used as a wholesome food in Lombardy by the lower classes. In Norway, during seasons of scarcity, the peasants eat chaff and the inner bark of pine trees, which are ground and baked to render them digestible. The woody fibre also of beech, birch, elm, lime, and poplar, will serve for diet when properly prepared. Acorns are said to be the principal vegetable food in California; and some nations find nourishment in earth. On the other hand, that the proscription of the productions of nature as food, by different nations, is frequently the result of prejudice, is exemplified in the facts collected by Dr. Truman.

"The inhabitants of several immense tracts of the globe entertain a marked distaste for milk; the Chinese, the inhabitants of Java, and of the other islands in the Indian Archipelago, have almost as great an aversion to it as we should have to blood; and similar objections extend also to cheese and butter among these people." (p. 29.)

Pork is eschewed by Mohammedans, Jews, and Copts, in whatever clime they live; and the ox by various castes of Hindoos,-by religious ordinances; and these articles of ordinary diet with us are, no doubt, from

education and long prejudice, by them disliked. Several tribes of people in Abyssinia have a perfect abhorrence of the flesh of the common fowl, and whole nations have rejected the use of fish.

Without professing to give credit to every account of cannibalism and geophagism recorded by travellers; or, in this place, to explain under what circumstances, for what length of time, and with what additions, chaff and earth can afford sustenance to mankind, it is quite clear that innumerable natural productions, not ordinarily so regarded, may be appropriately employed as food. The knowledge we have obtained of their constituent and alimentary principles teaches us in a great measure how, as a matter of course, it must be so, and reconciles numerous apparent inconsistencies. Extensive strata in various parts of the earth consist almost entirely of infusory animalcules, as shown by Ehrenberg; and, in particular, the "mountain meal" employed in Lapland, in 1832, with the bark of the birch tree and a little flour, for making bread, was discovered by Retzius to contain nineteen species. At present, our appreciation of the relative digestibility and of the nutritive value of these substances is very limited; but it is satisfactory to observe the investigation of these points in progress as a branch of science. In the mean time, not only must the remark quoted by Dr. Truman from Herschel be generally concurred in-that some of the facts before us "deserve a higher degree of celebrity than they have obtained, because they prove that absolute famine may be rendered next to impossible," but the question must force itself upon the reflecting mind; how is it possible, in a civilized community, that want and starvation should at any time be stalking abroad? Yet such things are.

From the time of Pliny, the natural history of the animals and vegetables from which food is derived, has been a subject of considerable interest with the medical practitioner; and the works of Tournefort and the Jussieus sufficiently established, from an early period, that the organic characters, the principles, and the virtues of plants are closely allied. The study of comparative anatomy and physiology has also its value. Dr. Pereira, on account of the extent of the subject, has purposely excluded all natural historical details. Dr. Davidson, on the contrary, professes to give them; in fact, they form a considerable part of his book. Nutriment may be distinguished from poison by an examination of the structure and analogies, and of the simple qualities of natural productions. We are willing to admit also that a knowledge of the native climate of our domestic animals, of their habits, propensities, modes of forming their nests, plumages, loves, &c., is all very proper for a medical man to be acquainted with; and Dr. Davidson's work will be found interesting in this way; but we do not quite understand that the pugnacity of lobsters, the manner in which fish is caught, or the method of storing away potatoes belongs, properly, to a Treatise on Diet,' by a grave physician.

Dr. Pereira arranges compound aliments under three primary divisions. 1, Solid foods, or aliments proper; 2, Liquid foods, or drinks; 3, Seasoning agents or condiments. This arrangement is not carried out very logically, for while broths and soups are classed as liquids, milk is placed amongst solids; it is, however, convenient, and the best, perhaps,

XXXIII-XVII.

in the present state of our knowledge, that could be devised. The first division has two sections; 1, Animal foods; 2, Vegetable foods.

1. Animal Foods. These are treated of in the order of the zoological classes, the author confining himself to animals employed as food in this country. Belonging to mammalia are the ox, sheep, hog, deer, rabbit, and hare. Of which it may be affirmed that the blood, the milk, many other fluids, and every structure, are called into requisition as alimentary substances. Bones, for instance, of which those of the ox and sheep are chiefly used in making soup, afford gelatin. But soup prepared from bones has higher nutritive powers than gelatin in its isolated state,-a circumstance to be accounted for upon a principle before adverted to,— complexity of composition; for bones yield phosphate and carbonate of lime, magnesia, soda, potassa, and also fat. Again, muscular flesh, or ordinary" butcher's-meat," must not be regarded as fibrin only, but as composed of tendon, aponeurosis, fascia, nerve, vessel, cellular tissue, blood, sinew, and fat; and as yielding to the organs of primary digestion, aqueous, saline, fatty, gelatinous, and proteinaceous alimentary principles. Of birds, a very large number are employed as food; the more important being the common fowl, the pheasant, partridge, pigeon, duck, and goose, of which the flesh, viscera, and eggs abound in albumen, fibrin, gelatin, and oil. The only reptile introduced is the green or edible turtle; the part eaten being rich in gelatin, and poor in fibrin. From the class of fishes, man obtains an endless variety of food, some nations, both in ancient and modern times, deriving from it their chief sustenance. The parts employed are the gelatinous integument, the flesh, and the viscera. The flesh is watery, and composed of fibrin, albumen, and gelatin, sometimes mixed with oil, as in the salmon and the eel, the latter principle being more abundant in the thinner or abdominal parts than in the thicker or dorsal portions; hence the preference given by epicures to the thinnest part of salmon. The white curdy matter, observed between the flakes of boiled fresh fish, is a film of albumen, produced by the coagulation of the serous juices intervening between the muscular layers. Of the crustacea many are edible, having a white firm flesh, which contains much gelatin, as in the lobster, crawfish, crab, and shrimp. Lastly, of the mollusca, a few species only are used in this country; the oyster, mussel, and periwinkle may be mentioned as examples. The flesh of the oyster, according to the analysis of Pasquier, contains fibrin, albumen, gelatin, osmazome, mucus, water, and salts.

The composition and qualities of the particular articles of animal diet vary exceedingly. Dr. Pereira has collected a few analyses, but it must be confessed that this part of organic chemistry has not at present been very completely followed out; we can only illustrate some of its results in their application to dietetics. It has already been shown that animal foods exhibit considerable differences in the quantity and proportions of their elements, and of those more essential organic compounds which have been called alimentary principles, and, accordingly, in their nutritive powers. Water is the largest constituent. Dr. Pereira remarks that, as 100 parts of the flesh of the oyster contain only 12.6 parts of solid matter, while 100 parts of butcher's meat contain, on an average, about