801 



FOOD. 



FOOD. 



862 



necessity for the supply of one to the exclusion of the other." 

 (Lankester, ' Letters on Diet.') 



Of the three forms of protein referred to above, fibrine is found in 

 the flesh and blood of all animals, ag gluten in wheat, barley, oats, rye, 

 and the other Cerealia. Albumen is found in the juices of many plants, 

 as cabbage, cauliflower, asparagus, &c. ; it is also found in the nervous 

 system and blood of animals. Casein is present in milk, also in the 

 seeds of leguminous plants, as peas, beans, and lentils. 



In the animal body is found a substance called Gelatin, which 

 appears to be formed out of the proteinaceous tissues. [GELATIN.] 

 This substance is necessary to the existence of the animal body, and 

 what cellulose is in the vegetable kingdom, gelatin appears to be in 

 the animal kingdom. Although often taken into the system with 

 animal food, especially in soups and jellies, there appears to be no 

 evidence that it is even converted into a proteinaceous tissue. Experi- 

 ments on this subject have been performed both in France and 

 Belgium on an extensive scale, and the conclusion arrived at was the 

 same, that gelatin is not used for forming auy of the proteinaceous 

 tissues of the body ; at the same time it is not improbable that the 

 gelatin may be appropriated for the purpose of renewing the gelati- 

 nous portions of the tissues, which are very extensive in the animal 

 body. 



It will be thus seen that although gelatin cannot be said to be 

 nutritious in the sense of nourishing the actively vital parts of the 

 body, it may assist in keeping up certain parts of the fabric. It need 

 not then be rejected from our food ; but it cannot be too widely known, 

 that, as the basis of soups and jellies, it may be administered under 

 the supposition of its being nutritious, and thus lead, if used alone in 

 diet, to disastrous results. 



Of the forms of protein which occur in food, Casein demands a 

 short notice. Although, as dissolved in milk, it is very digestible, it 

 becomes, when separated and known by the name of cheese, very 

 indigestible. When milk is deprived of its butter, and the pure 

 casein made into cheese, as is the case with some English cheeses, as 

 those from Suffolk, it becomes so hard as scarcely to be digestible. 

 [CIIEKSE, in ARTS AND Sc. Div.] But in most cases the casein is 

 curdled with the butter, and a large per-centage of this substance is 

 found in all good cheeses. Stilton cheese is made by adding the 

 cream of one milking to that of another, so that this cheese has double 

 the quantity of butter that other cheeses possess. The indigestibility 

 of separated or insoluble casein will perhaps explain the neglect of 

 beans, peas, and lentils, ag articles of diet, although they contain a 

 much larger quantity of nutritious ingredients than most seeds. 



In concluding these general remarks upon diet, we present our 

 readers with a summary of the conclusions on this subject arrived at 

 by one of our most recent physiological writers. Dr. Carpenter, in 

 his ' Principles of General and Comparative Physiology,' thus concludes 

 this part of his subject : 



" The waste of the tissues, of which gelatin is the basis, may be 

 supplied either by albuminous, proteinaceous, or gelatinous compounds, 

 since there is no doubt that albumen may be converted into gelatin, 

 although the reverse process cannot be performed. As gelatin does 

 not exist in plants, it must be formed in herbivorous animals at the 

 expense of the albuminous elements of their food ; whilst in carnivo- 

 rous animals it is probably derived immediately from the gelatinous 

 components of the bodies on which they prey. The materials of the 

 adipose tissue, and the oleaginous particles which seem requisite in 

 the formative operations of the system, generally are derived in the 

 carnivorous races from the fatty substances which the bodies of their 

 victims may contain ; whilst the herbivorous not only find them in 

 the oleaginous state in their food, but have the power of producing 

 them by the conversion of farinaceous and saccharine matters. 



" The foregoing statements are applicable to all tribes of animals 

 ' cold-blooded ' as well as ' warm-blooded.' We have now to consider 

 the special case of the latter. In the carnivorous tribes the waste of 

 the tissues is so great, in consequence of the restless activity which is 

 habitual to them, that it appears to furnish a large proportion of the 

 combustible material required for the maintenance of their proper 

 temperature. The remainder is made up by the fat of the animals 

 on which they feed ; and it is to be observed that the amount of this 

 i much greater in the bodies of animals inhabiting the colder regions 

 of the globe than in the inhabitants of tropical countries. In the 

 herbivorous tribes the case is different : they are for the most part 

 miih leas active ; and the waste of their tissues consequently takes 

 place in a less rapid manner, and is far from supplying an adequate 

 amount of combustible material, especially in cold climates. Their 

 heat is in great part sustained by the combustion of the saccharine 

 and oleaginous elements of their food, which are appropriated to this 

 purpose without having ever formed part of the living tissues ; and 

 the demand for these will be larger in proportion to the depression of 

 the external temperature, a greater generation of caloric being then 

 required to keep up the heat of the body to its proper standard. 

 Hence, cold-blooded annuals can usually sustain the privation of 

 food longer than warm-blooded, and this more especially when they are 

 kept cool, to that they are made to live slowly, and death when at last 

 it does eniue is consequent upon the general deficiency of nutrition. 

 On the other hand, warm-blooded animals, whose temperature is 

 uniformly high, must always live fast, and deprivation of food is fatal 



to them, not only by preventing the due renovation of their tissues, 

 but also by destroying their power of sustaining their heat. The 

 duration of life under these circumstances depends upon the amount 

 of fat previously stored up in the body, and upon the retardation of 

 its expenditure by external warmth, or by the inclosure of the body 

 in non-conducting substances ; and there is evidence that if this be 

 duly provided for, and all unnecessary waste by uervo-muscular 

 activity be prevented, the life even of a warm-blooded animal may 

 sometimes be prolonged for many weeks without food." 



It will be gathered from the foregoing general remarks that food 

 may be divided into two great classes the heat-giving and the flesh- 

 forming ; and we now present a table of some of the more ordinary 

 kinds of food, in which one or the other, or both, of these classes of 

 substances are found mixed : 



Table of Composition of Food in 100 parti. 



100 grains of Tea give in an infusion 5 grains of theine and 26'5 

 grains of non-nitrogenous substances. (Peligot.) 



By adding the first three columns of this table together, and 

 deducting the sum from one. hundred, it will give the quantity of 

 water contained in each article of food. Thus, taking butcher's 



meat : 



Nitrogeneous material 

 Carbonaceous material 

 Mineral Matter 



Water 



22-3 



14-3 



5 



37-1 

 62-9 



100-0 



The quantity of carbon expresses the relative heat-giving power of 

 the food. With foods containing fat the quantity of hydrogen should 

 also be taken into consideration. 



Such a table as this will be found useful in constructing dietaries 

 for large institutions, which are very often erroneously constituted, 

 and a large waste thereby entailed. The table on the next page 

 contains examples of dietaries, drawn up by Dr. Lyon Playfair, from 

 various sources. This table accompanied an abstract of a lecture by 

 Dr. Lyon Playfair on the 'Food of Man,' delivered at the Royal 

 Institution in May 1853. The following extracts from this lecture 

 will explain some of the valuable results obtained by Dr. Playfair : 



" It was now admitted that the heat of the body was due to the 

 combustion of the unazotised ingredients of food. Man inspires 

 annually about 7cwt. of oxygen, and about l-5th of this burns some 

 constituent and produces heat. The whole carbon in the blood would 

 thus be burned away in about three days unless new fuel were 

 introduced as food. The amount of food necessary depends upon 

 the number of respirations, the rapidity of the pulsations, and the 

 relative capacity of the lungs. Cold increases the number of respi- 

 rations and heat diminishes them ; and the lecturer cited well-known 

 cases of the voracity of residents in arctic regions, although he 

 admitted, as an anomaly, that the inhabitants of tropical climates 

 often show a predilection for fatty or carbonaceous bodies. He then 

 drew attention to the extraordinary records of arctic dietaries shown 

 in the table, which, admitting that they are extreme cases even in the 

 arctic regions, are nevetheless very surprising. 



" Dr. Playfair then alluded to the second great class of food 

 ingredients, namely, those of the same composition as flesh. Beccaria 

 in 1742 pointed to the close resemblance between these ingredients of 



