prescription. In considering the case of the white cow, we find that a change from barley to barley and molasses increased the milk in three days from 211b. 6 oz. to 23 lb. 7 oz.; on changing from malt to barley it increased from 19 lb. 10 oz. to 20 lbs. 11 oz. on the first day: from barley to barley and linseed, it increased from 21 lb. 2 oz. to 23 lb. 12 oz. on the sixth day: from barley and linseed to beans, it increased on the first day from 21 lbs. 13 oz. to 23 lbs. 14 oz.” P. 147.

We consider the foregoing extract of high importance, in pointing to an omission entailing much needless suffering. Many poor-law and prison dietaries are constructed with sufficient liberality as regards quantity, but in utter neglect of the no less important item variety. The same unvaried routine is the doom of the unfortunate inmates, the severity of which may be judged of by the palling effect which the too frequent repetition of even the most excellent dishes exerts upon the palates of persons not condemned to the miseries of inaction. Common humanity demands that this matter shall be looked into, especially as the rectification of the error involves no additional expense, inasmuch as Dr. Thomson suggests some cheap varieties, and others might be easily added.

Dr. Thomson suggests Calorifiant or Heat-producing as a more suitable term for designating the Elements of the food termed Respiratory by Liebig, and the following are some of his observations upon the proportion which these hold to the Nitrogenized or Nutritive Elements.

"Milk, the food of the infant mammalia, contains one part of nutritive to two parts of calorifiant constituents, and in the young state of an animal the nutritive part of the food not only supplies the place of the metamorphosed solids, but an additional amount of it is required to increase the bulk of the individual; and, as we have already stated that animal heat is generated by the change or degradation of the fibrinous tissues, it is obvious that, in the nourishment of infant life, there is a supply of heat, from the casein, vastly superior to that afforded by fibrin supplied to full-grown animals, because the amount taken in proportion to the quantity of calorifiant matter is much greater. If we refer, again, to the food which is generally employed by the inhabitants of this country, wheat and barley, we find, by a mean of experiments afterwards to be detailed, that the average amount of albuminous matter present in them is 11 per cent., while the quantity of starch and sugar existing in those substances may vary from 70 to 80 per cent. : thus affording the proportion of nutritive to calorifiant food as 1 to 7 and upwards. Such food, it may be inferred, is fitted for the consumption of an animal which is not subjected to much exercise of the muscular system, and may be viewed as the limit of excess of the calorifiant, over the nutritive constituents of food. As the demands upon the muscular part of the frame become more urgent, the proportion of the azotized constituents should be increased, and this may be extended until we arrive at the point where the fibrinous matter is equal to the half of the calorifiant, which is probably, in a perfectly normal physiology, the greatest relative proportion of nutritive material admissible." P. 165.

Dr. Thomson observes that, in order to vary the nature of the food according to the rest or activity of the animal, tables of its composition are essential, and he presents a short one founded upon his own experiments. From this, it appears that the relative proportions of nutritive to calorifiant matter in various articles of diet are as follow:-Milk 1 to 2; Beans 1 to 2; Oatmeal 1 to 5; Barley and Semolina 1 to 7 ; English Wheat Flour 1 to 8; Potatoes 1 to 9; Rice 1 to 10; Turnips 1 to 11; Arrow-root, Tapioca, and Sago 1 to 26; Starch 1 to 40. From the ac

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On the Food of Children.

145 companying remarks we select the following interesting ones on the Food of Children.

"Hence we learn that milk, in some form or other, is the true food of children, and that the use of arrow-root, or any members of the starch class, where the relation of the nutritive to the calorifiant matter is as 1 to 26, instead of being as 1 to 2, by an animal placed in the circumstances of a human infant, is opposed to the principles unfolded by the preceding table. In making this statement, I find that there are certain misapprehensions into which medical men are apt to be led at the first view of the subject. To render it clearer, let us recal to mind what the arrow-root class of diet consists of. Arrow-root and Tapioca are prepared by washing the roots of certain plants until all the matter soluble in water is removed. Now, as albumen is soluble in water, this form of nutritive matter must in a great measure be washed away: under this aspect we might view the original root before it was subjected to the washing process, to approximate in its composition to that of flour. If the latter substance were washed by repeated additions of water the nitrogenous or nutritive ingredients would be separated from the starchy or calorifiant elements, being partly soluble in water, and partly mechanically removed. Arrow-root, therefore, may be considered as flour deprived as much as possible of its nutritive matter. When we administer arrowroot to a child it is equivalent to washing all the nutritive matter out of bread, flour, or oatmeal, and supplying it with starch: or it is the same thing approximatively as if we gave it starch: and this is in fact what is done, when children are fed upon what is sold in the shops under the title of Farinaceous Food,' empirical preparations of which no one can understand the composition without analysis. Of the bad effects produced in children by the use of these most exceptionable mixtures, I have had ample opportunities of forming an opinion, and I am inclined to infer that many of the irregularities of the bowels, the production of wind, &c. in children, are often attributable to the use of such unnatural species of food. It should be remembered that all starchy food deprived of nutritive matter is of artificial production, and scarcely, if ever, exists in nature in an isolated form. The administration of the arrow-root class is therefore only admissible when a sufficient amount of nutritive matter has previously been introduced into the digestive organs, or when it is inadvisable to supply nutrition to the system, as in cases of inflammatory action. In such cases, the animal heat must be kept up, and for this purpose calorifiant food alone is necessary. This treatment is equivalent to removing blood from the system, since the waste of the fibrinous tissues goes on, while an adequate reparation is not sustained by the introduction of nutritive food. A certain amount of muscular sustentation is still, however, effected by the arrow-root diet; since, according to the preceding tables, it contains about one-third as much nutritive matter as some wheat flours. The extensive use of Oatmeal, which is attended with such wholesome consequences among the children of all ranks in Scotland, is, however, an important fact, deserving serious consideration: and, it appears to me, is strongly corroborative of the principles which I have endeavoured to lay down in the preceding pages." P. 169–171.

Dr. Thomson offers several useful observations upon the making of breads by the admixture of various flours, and is, we are glad to find, an advocate for the manufacture of this article independently of fermentation. If the experiments which have been recently so extensively undertaken prove successful, the boon conferred upon humanity will not be inconsiderable, when we consider the facility with which fresh-bread may be made on ship-board, and the emancipation of that numerous class of persons the journeymen bakers from their destructive nocturnal toils. We believe the experience of most persons who have tried it is in favour of the

NEW SERIES, NO. IX.-v.

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comparatively greater wholesomeness of unfermented bread, and Dr. Thomson, as the result of his investigations, finds its production more economical than is that of the fermented :—a sack of flour yielding 107 loaves of unfermented, and but 100 of fermented bread; 6 per cent. being lost by the ordinary process of baking. He furnishes the following formula for making unfermented bread.

"Take of Flour 4 pounds, Sesquicarbonate of Soda 320 grains, Hydrochloric Acid 6 fluid-drachms, Common Salt 300 grains, Water 35 ozs. by measure. The Soda is first mixed with the Flour very intimately. The Salt is dissolved in the water, and added to the Acid. The whole is then rapidly mixed as in common baking. The bread may be either baked in tins or formed like cottage loaves, and should be kept from one to two hours in the oven. Should it prove yellow, it is a proof that the soda has been in excess, and indicates the propriety of adding a small additional portion of acid; the acid varying somewhat in strength." P. 185.

We now proceed to the consideration of Baron Liebig's observations upon "The Mutual Relations of Chemistry and Physics to Physiology and Pathology," as contained in his new Chapter upon the mode in which the investigation of the Metamorphoses of Animal Tissues should be pursued. It is an excellent chapter, full of sound philosophy, and we are much pleased to find it's author acknowledging himself so much indebted to that admirable work, "Mill's System of Logic," during its composition. "Indeed, he feels that he can claim no other merit than that of having applied to some special cases, and carried out, further than had been previously done, those principles of research in natural science which have been laid down by that distinguished philosopher." Did works of this stamp more frequently form a portion of the preliminary studies and future references of the members of our profession, we should be spared many a crude theory and disjointed hypothesis, and should seldomer see them entangled in the mazes of sophistical reasoning and profitless speculation.

To proceed: Although in certain of the natural sciences the mutual relations of their phenomena have been observed with sufficient minuteness and accuracy to permit, by the special laws thus accumulated, the safe deduction of general laws, competent to the explanation of new phenomena and observations; such a point has not been reached as respects Physiology. To render it a deductive science, however, precisely the same procedures are requisite, and its progresss is retarded by the same obstacles which have impeded that of other branches of science. Of these the difficulty of overcoming preconceived opinions by reason of some imperfection of information defying comprehension is the greatest; and thus many now well-established and easily understood facts of science positively defied at one time the comprehension of the most sagacious minds.

"We thus perceive that the comprehensible' has nothing whatever to do with the phenomenon. It depends upon the state of the development of the intellect. When, to the observer, the connecting link is wanting, which attaches a fact to the ordinary course of thought, then the fact, to his view, is destitute of truth or comprehensibility. This is one of the greatest obstacles which impedes the application of Chemistry to Physiology, or the simple study of chemical discoveries on the part of many physiologists. To this must be added, in Pathology, the holding for true of observations, the accuracy of which has no

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Necessity of practised Observation.

147

other support than this, that they have been held as true for a thousand years. If, in these branches of knowledge, the methods of proof and investigation be not changed, there is no hope, with all her progress, Chemistry can ever be capable of yielding essential advantages to Physiology and Pathology; and yet it is impossible that these branches can ever acquire a scientific foundation, without the aid of Chemistry and Physic. Everyone feels the necessity: it is only concerning the mode of application of these sciences that men are not agreed." P. 162.

Thus

One great cause of the modern progress of Chemistry consists in the acknowledgment of a plurality of causes of its various conditions, in contradistinction to the essential properties of the older chemists; but too many physiologists and pathologists of the present day comprehend under the terms Nervous Force, Vegetation, Irritation, &c. so many independent existences analogous to the essences of the phlogisticians. the terms endosmose and exosmose are regarded, not merely as expressive of one of the modes of filtration, but as denoting essential properties. Although it should be a primary object to distinguish the various conditions upon which the phenomena of vitality depend, and this principle is often applied in modern physiological investigations, yet M. Liebig, in a critical commentary upon the doctrines of Irritation, delivered by Professor Henle in his Pathology, shows that, even at the present time, very opposite conditions are often confounded together under some ill-defined or paraphrasistical term, false analogies and comparisons being also frequently resorted to. We have not space to follow him through this exposition, but may quote a short passage.

"A rude image of the organism, in many of its relations, may be found in the great sea-going steam-vessels. These consume, at each moment of their voyage, oxygen and fuel, which are given out in the form of carbonic acid, water, and soot or smoke. In them, exists a source of heat and a source of power which produces motion, or prepares the food of the crew; and when a sail is torn, there is a man at hand to repair it: a leak is stopped by the carpenter: blacksmiths and other hands are active to preserve the ship in her original state and in motion. So, also, in the living body, there are smiths and carpenters at work, and the problem is, to acquire a knowledge of them, and of their mutual relations." P. 177.

An exercised condition of the perceptive powers is an essential condition for accurate observation; and no merely theoretical views in Chemistry or Physics will be received at the hands of one who has not given, by his prior practical investigations, assurance of his powers of correct appreciation." It required a Berzelius, with his acute perceptive powers, to save from oblivion the notions of Richter concerning chemical proportions, to recognize their interior truth, and the existence of an universal law of combination under a mass of false facts, of which a single example-that of the carbonate of alumina, employed as the starting-point of the first table of equivalents, which salt does not exist, was sufficient to destroy all belief in the more accurate remaining facts.' We cannot do better than quote the following excellent remarks upon erroneous observation.

"From the point of view of true natural philosophy every erroneous mode of contemplation and interpretation depends on the want of correct observations and on the false notion entertained of the nature of an observation. It further depends on this, that we regard the constant association of two things, or the

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constant occurrence simultaneously of two phenomena, as a necessary connection, and consider them as mutually determining one another. In nature, a number of phenomena appear together, one of which is not perceived when the other is wanting, but there are numberless others which occur together, without the remotest connection. The supposition of a relation thus fallacious, or a false nexus causalis proceeds in all cases from a false method of observation. So, also, the association of two phenomena, which are only analogous in one solitary relation, is always the result of imperfect observation.

"To see, to perceive by means of our senses, is one condition of observing: but seeing and perception do not characterize true observation. The problem to be solved by the observer, is, not merely to see the thing, but also the parts of which it consists. A good observer must notice and seek to convince himself, in what connection the facts stand to each other and to the whole." P. 183.

Several examples of erroneous observation are adduced; but the one commented upon at greatest length, is that furnished by the parasitic theory of contagion. In opposition to this, the author first states the facts favorable to the chemical theory of contagion, giving a luminous account of the origin and bearings of ferments and putrefaction. To the question of whether the state of transformation or putrefaction may be propagated to the living organism? he believes facts answer affirmatively. Among these are the effects of wounds received during dissection, and the symptoms induced by the ingestion of food in a state of decomposition, as German sausages, &c. The products of disease so induced are neither more or less than portions of the constituents of the frame in a state of change in form or composition, and by means of such matters, so long as the state of decomposition continues, may the disease be propagated to others. Moreover, antiseptic substances powerful in checking putrefaction are those best adapted to destroy the communicability of contagions; while ammonia, the common product of putrefaction, is abundantly discharged from the system in typhus. Finally, the origin of epidemic and miasmatic disease in localities wherein decomposition of organic matters is going on is familiar to all observers.

"Hence, according to all the rules of scientific investigation, the conclusion is fully justified, that in all cases where a process of putrefaction precedes the occurrence of a disease, or where the disease can be propagated by solid, liquid, or aeriform products of disease, and where no nearer cause of this disease can be discovered, the substances in a state of decomposition or transformation must be regarded as being, in consequence of that state, the proximate causes of the disease. The condition which determines, in a second individual, his liability to the contagion, is the presence, in his body of a substance, which, by itself, or by means of the vital force acting in the organism, offers no resistance to the cause of change in form and composition operating on it. If this substance be a necessary constituent of the body, then the disease must be communicable to all persons; if it be an accidental constituent, then only those persons will be attacked by the disease, in whom it is present in the proper quantity, and of the proper composition. The course of the disease is the destruction and removal of this substance; it is the establishment of an equilibrium between the cause acting in the organism, which determines the normal performance of its functions, and a foreign power, by whose influence these functions are altered." P. 206.

The author is quite at a loss to imagine how the parasitic theory of contagion can be preferred by any enquirer to the one above stated. It is based upon two facts, the propagation of scabies, and the occurrence of