390 



STOMACH AND INTESTINE. 



examined. The muscular substance of Fishes 

 contains a still greater quantity of albumen. 

 That of the young of most animals is softer, 

 and its fibres smaller and more digestible, 

 than the flesh of the adult. 



The artificial preparation of animal food 

 for the table probably induces a variety of 

 chemical changes. But the full import of these 

 changes has yet to be made out. At pre- 

 sent, we know little except some of the more 

 obvious physical results which attend the 

 processes of cooking. These are best seen 

 in the cooking of meat. 



The increased digestibility of meat which 

 has been killed some time previously to being 

 eaten, seems to depend, partly on the more 

 uniform and softer consistence imparted by 

 the diffusion of its juices, and partly on the 

 imperfect decomposition which it has begun 

 to undergo. The latter change to some ex- 

 tent prepares it for digestion, by rendering it 

 more soluble. But any approach to abso- 

 lute putrefaction reverses this advantage ; at 

 any rate, in the case of Man, whose natural 

 judgment would probably in most instances 

 lead him to reject putrid meat, as alike dis- 

 gusting to the senses, hurtful to digestion, 

 and dangerous to health. 



In the operation of roasting meat, the heat 

 applied to the exterior of the mass soon con- 

 verts its superficial portion into a dense, hard 

 substance. This compact crust consists chiefly 

 of albumen which has been coagulated by heat. 

 It is of essential service, not only in mode- 

 rating the heat afterwards applied through it 

 to the deeper portions of the meat, but also 

 in retaining its various liquid and volatile pro- 

 ducts, which would otherwise be soon dissi- 

 pated in the gaseous or vaporous form. 

 The moderate heat which permeates the mass 

 probably aids the various juices of the meat 

 in diffusing themselves throughout its whole 

 texture ; increasing its uniformity of consist- 

 ence, and dissolving much of its gelatinous 

 tissues. Its albumen is always more or less 

 coagulated by the heat ; though, where much 

 blood is present, the colour and fluidity which 

 it sometimes retains, appear to indicate an 

 imperfect character of this change.* A variety 

 of empyreumatic substances, which are de- 

 veloped chiefly in the more heated exterior 

 of the mass, next add the savoury odour 

 and deepened colour, so characteristic of this 

 method of cooking. If the process be unduly 

 protracted, it will obviously burn the harder 

 outside shell, and render the coagulated and 

 contracted mass within too dense, tough, and 

 insoluble for easy digestion ; while, if con- 

 ducted too rapiJly, the same combustion of 

 the outside is of course attended with the loss 

 of all the advantages of cooking in the raw 

 central portion. 



The changes induced by boiling meat, 



* This imperfect coagulation has been supposed to 

 prove that the heat (15-i) at which the blood coa- 

 gulates, has not been attained. But the appearances 

 in meat boiled at 212, and the temperature of roast 

 meat itself, render 9 ich a view very doubtful. 



partially resemble those which are caused 

 by roasting it. For both of these processes 

 are probably accompanied by a coagulation 

 of albumen, a solution of osmazom, and a 

 formation of gelatine in the muss itself. 

 But they differ greatly from each other in 

 many respects. From the lower tempera- 

 ture applied in boiling, no empyreumatic sub- 

 stances are developed ; while the water 

 which conveys the heat to the mass always 

 extracts from it a certain proportion of its 

 soluble constituents. This extraction may 

 be to some extent diminished by suddenly 

 plunging the meat into boiling water, so 

 as to coagulate the albumen of its outer- 

 most layers ; and conversely, the extractive 

 process may be favoured, not fhily by in- 

 creasing the surface of contact, but also by 

 delaying the coagulation of the albumen, and 

 prolonging the period of the solvent action. 

 Hence, where it is chiefly the broth or watery 

 solution of the meat which is intended to be 

 used as food, the mass is preferably cut in 

 very small pieces, and the temperature of 

 the water raised very slowly to a degree of 

 heat short of ebullition, and maintained there 

 for a long time. 



The various modes of salting and smoking 

 meat are chiefly intended to protect it from 

 decomposition ; hence they scarcely require 

 much notice here. In the former process, 

 however, the qualities of the meat appear 

 seriously damaged *, quite apart from the 

 mechanical disadvantages which both it and 

 smoking often impart. 



Fat. In a purely animal diet, the amount of 

 this oleaginous constituent is of indispensable 

 importance. For, with the exception of that 

 minute quantity of inosit or muscular sugar 

 which is proper to the sarcous substance, the 

 fatty matters contained in the various tissues 

 of the body are the only representatives of 

 the two groups of the hydro-carbons and hy- 

 drates of carbon, which this kind of food 

 possesses. Hence the fat of such a diet has 

 to replace, as it were, the starch of the vege- 

 tables which usually enter into a mixed diet ; 

 and thus constitutes the sole non-azotized or 

 respiratory element of animal food. 



And even in what are often miscalled vege- 

 table diets, a large quantity of this animal sub- 

 stance is commonly added to the other ingre- 

 dients of the food. At least there seems to 

 be a strong impulse towards such an admix- 

 ture in most of the vegetarian nations and 

 races of modern times : an impulse which 

 is well exemplified in the butter or ghee so 

 copiously added by the Hindoo to the rice 

 that forms his staple food. 



The quantity of fatty matter which may 

 thus be taken into the system can scarcely 

 have any definite limit assigned to it. In the 

 Arctic climates it appears to attain a very 



* The liability of persons fed on such meat to 

 scurvy, can scarcely be exclusively referred to 

 the privation of vegetables. For large numbers 

 of people appear to subsist with impunity on fresh 

 meat only (see p. 388.). 



