A Sci 3290. 17 CE LIBRARY PRINTED BY COMPTON AND RITCHIE, MIDDLE STREET, CLOTH FAIR. THE Medical Session commenced at this Institution on Monday, November 11th, 1844. The Introductory Address was delivered by Mr. Morton. The theatre was unusually full, and many practitioners of veterinary medicine were present. The lecturer, after offering some admonitory advice to the student, and placing before him the course of study to be adopted, proceeded cursorily to review the so-called elements of the ancients,—fire, air, earth, and water. After describing the constituents of the three last named, and exhibiting their characteristic properties, he shewed how they exist in organic substances, making up the varied principles found both in vegetables and animals, the atmosphere being the mysterious bond that connects the two kingdoms of nature, the organic and inorganic; one of the links of the chain that binds Prometheus to the rock. From the air plants derive their sustenance and support; on these the herbivora feed, which become food for the carnivora, and thus the animal organism generates not a single principle. The elementary substances are first absorbed and assimilated by vegetables, whence result certain compound bodies designated proximate principles; and among these proteine and its compounds occupy a prominent place. According to Professor Mulder, its discoverer, proteine is found in various parts of plants-in the roots, stems, leaves, and fruit, and also the sap; and in three different conditions, one soluble in water, the other insoluble in this menstruum, and the third soluble in alcohol. Its empirical formula is C40 H62, N10, O12 Thus shewing what a large number of atoms are congregated to gether to form a single proximate principle, and how disposed the same is to undergo chemical change when certain conditional circumstances are removed; whence result new compounds, most of them being binary in their nature. Rarely is it the case that proteine exists pure in vegetables it is united with phosphorus and sulphur, but the manner of combination is ill understood. The compounds there formed are, vegetable albumen, vegetable fibrine, and vegetable caseine, with gluten. The analogies of these in the animal are, animal fibrine, albumen, and caseine; and the difference between the principles are very minute proportions of sulphur and phosphorus. These principles or compounds of proteine being found in the blood, it might be anticipated that other parts of the frame would be constituted of them, and it has been ascertained that animal fibre is a proteine compound: in the brain, liver, kidneys, and many other organs, the same compound is also met with under the form of albumen; and we find a similar one to exist in horns, nails, hairs, and cuticle. These principles are, in fact, the bases of the nitrogenized constituents of the animal frame; the neutral quaternary organic principles of Dumas and Boussingault. In contradistinction to these, in the vegetable are met with what are designated ternary compounds; and under this head are placed woody fibre, starch, or dextrine, and the varieties of sugar, with certain bodies obtained from these; all of which are made up of carbon, hydrogen, and oxygen, varying not very considerably in the quantities of each, yet, their molecules being differently arranged, dissimilar compounds are formed; still they are easily convertible the one into the other. These are partaken of by animals, and either undergo combustion within the living organism, to keep up the heat of the body, which is essential to life; or their elements are deposited in the form of fat, the supply of oxygen not being sufficient for the first named purpose, or nature not requiring it. "The stall fed animal," says Liebig, "eats, and reposes merely for digestion. It devours, in the shape of nitrogenized compounds, far more food than is required for reproduction or the supply of waste alone; and, at the same time, it eats far more of substances devoid of nitrogen than is necessary merely to support respiration, and to keep up animal heat. Want of exercise and diminished cooling are equivalent to a deficient supply of oxygen; for when these circumstances occur, the animal absorbs much less oxygen than is required to convert into carbonic acid the carbon of the substances destined for respiration. Only a small part of the excess of carbon thus occasioned is expelled from the body of the horse and ox in the form of hippuric acid; and all the remainder is employed in the production of a substance which, in a normal state, only occurs in small quantity, as a constituent of the nerves and brain: this substance is fat." Again, he says, "It is evident that the formation of fat in the animal body is the result of a want of due proportion between the food taken into the stomach and the oxygen absorbed by the lungs and skin.” This has led him to divide all alimentary substances into two classes, under the heads of Elements of Nutrition, and Elements of Respiration. On the other hand, Dumas asserts, that fat, like all other animal principles, is generated by vegetables; "that they pass ready formed from them into the bodies of animals, that there they may either be burnt immediately, in order to supply the heat which the animal requires, or that they may be laid up in the tissues more or less modified, to serve as a reserve for respiration. With a view to verify this idea, we instituted many experiments, which all led us to recognise in the food of the herbivorous animals subjected to experiment, quantities of fatty matter superior to those found in the milk of the milch-cow, for example, or stored up in the tissues of the ox put up to fatten. By keeping an account of the fatty matter contained in the dung, and adding it to the quantity fixed, the sum obtained is still inferior to the quantity of fat which analysis discovers in the food of the animal. With these facts before us, it appeared to us natural to admit that animals assimilated directly the fatty substances of vegetables without modifying them at all, or modifying them but little.” The truth is, the formation of fat in animals has awakened a controversy between the two great chemists of Germany and France,-Liebig and Dumas. Liebig is of opinion, as has been already stated, that graminivorous animals produce fat from the elements of starch or sugar partaken of by them, these Nor being burnt up by the oxygen taken in during respiration; while Dumas, : with whom is associated Boussingault, considers it a fixed rule that animals produce neither fat nor any other substance capable of ministering to nutrition, but that every principle exists ready formed in the vegetables on which the animals feed and certainly the multiplied and delicate analysis they have made of hay, maize, and other provender given to fatten cattle, fowls, &c., prove the existence of a substance closely resembling fat, as one of their constituents. They contend that the fatty matters are elaborated in the leaves of plants in the form of a waxy principle, which, passing into the bodies of the hebivora, undergoes a partial oxidation, whence result the stearic and oleic acids met with in tallow. In carnivorous animals these are oxidised anew, and margaric acid is formed, which characterises their fat. Lastly, by a still higher oxidation, the volatile fat acids are formed which appear in the blood and perspiration. This difference of opinion appears likely to be set at rest by a discovery lately made by Pelouge and Gelis, which is, that butyric acid-an acid hitherto derived from animal fat-may be formed by modifying the fermentation of sugar. This particular result is brought about by the presence of caseine in the matter undergoing the process of fermentation, and " the change of sugar into butyric acid takes place without any considerable increase of temperature, and without the presence of those energetic substances which could destroy the equilibrium or affect the vitality of the animal tissues; while this transformation is effected under very simple conditions, and in substances employed by Nature herself." Now, if we associate with this the fact, that farinaceous matters undergo a ready conversion into a saccharine principle, we have a clue to explain how it is that these substances become so fattening to animals as it is well known they do. The lecturer next proceeded to shew how digestion and other functions carried on in the animal economy receive elucidation by an application of chemical laws; also the formation of the various secretions, with their uses, particularly referring to bile and urine. Of the first of these he remarked: The use of bile in the living organism has been the subject of |