396 



STOMACH AND INTESTINE. 



habitual ingestion in company with other 

 articles of diet, and the manner in which they 

 modify nutrition, forbid them to be passed 

 over unnoticed. 



Tea and Coffee. Tea and coffee present 

 a marked similarity, not only in their com- 

 position, but also in that action on the ner- 

 vous system which is their chief physio- 

 logical effect on the organism. Both consist of 

 an oil, with a certain quantity of tannin, united 

 to an azotized vegetable alkaloid ; which 

 is called thein, or caff'ein, respectively, but 

 possesses the same composition in both (C 46 

 H 10 N 4 O 4 ). As regards their effects on the 

 system, both produce sleeplessness and cere- 

 bral excitement. But coffee stimulates the 

 circulation much more strongly, and in some 

 persons excites diarrhoea. While tea is more 

 apt to produce muscular tremors and irre- 

 gular cardiac action ; and generally causes 

 a constipation rather than a relaxation of the 

 bowels. The dietetic use of the two is very 

 similar. How far they promote digestion is 

 doubtful. They seem, however, to lessen 

 the drowsiness and cerebral inaction which 

 often follow the ingestion of a large meal. 

 Like alcohol, they probably* diminish the rate 

 of waste of the tissues generally. 



Alcohol in all its various forms whether of 

 beer, wine, liqueur, or spirits is equally un- 

 deserving of the name of food. It is not a 

 nutritious article of diet ; but rather a drug, 

 which has a specific stimulating action on 

 the nervous system. As regards its ultimate 

 destinv in the organism, it seems certain that a 

 part of it leaves the body, unchanged, in the 

 exhalations of the skin and lungs. 



The fermented liquors enumerated above 

 are generally taken with the food. And in 

 many of them, the alcohol is associated 

 with small quantities of sugar and other 

 alimentary substances. Their several tastes 

 and odours are due partly to these, partly 

 to other admixtures : such as the bitter 

 of the hop in beer, oenanthic aether in wine, 

 and the various products of distillation in 

 ardent spirits. The per centage of alcohol 

 in these different liquids may be estimated as 

 being, on an average, 3 to 7 in beers ; 7 to 20 

 in wines ; and 20 to 50 in spirits. 



Dietaries. In ending this cursory view of 

 the different alimentary substances, we may 

 briefly inquire into the quantity and quality of 

 the food which would be the result of their 

 admixture with each other, in the proportions 

 best suited to the maintenance of health. 



From what has already been stated, it is 

 obvious that, in constructing such an ideal 

 diet, or in estimating the proper daily ration 

 which ought to form the food of any indivi- 

 dual or class of persons, it should be our first 

 care to ascertain the presence of all the ali- 

 mentary principles in suitable proportions. 



* Since the above was written, the experiments 

 of Boecker, Lehmann, and others, on which this 

 statement may now be regarded as based, have 

 been well discussed in an article in the Meclico- 

 Chirurgical Review for January, 1855. 



At first sight, it might seem easy to cal- 

 culate an efficient scale of diet, from no 

 other data but those which the above law 

 affords us. With these data, it might even 

 appear that such a knowledge of arith- 

 metic as is implied in knowing the rules of 

 simple addition and subtraction would enable 

 us to calculate an infinite number of dietaries. 

 For, it would evidently be easy for us to take 

 any forms of protein, hydrocarbon, or hy- 

 drate of carbon, and compare the known 

 per-centage of their elementary substances 

 with the similar elements of the carbonic acid 

 and urea which represent the most important 

 products of the waste of the bod}'. Adapting 

 the quantities of the former to those of the 

 latter, we might thus arrange thousands of for- 

 mulae, in which food would always cover waste, 

 and income exceed expenditure: formula 

 which, provided the human organism were 

 really made up of similar figures, would, no 

 doubt, give us equally definite and satisfactory 

 results when carried out into practice. 



A variety of circumstances, however, concur 

 to invalidate such calculations, and reduce 

 them to their true value: viz. the results of 

 a mere process of addition and subtraction, 

 that only distort and obscure the facts on 

 which they are founded. Such circumstances 

 prove, that the end of these sums in simple 

 arithmetic is no better than the beginning: 

 that they do but repeat, in a less specific, and 

 therefore less truthful form, the various state- 

 ments of the skilful chemist, on which they 

 are all based ; and that, if carried any further, 

 they can only mislead the physiologist. 



For instance, not all our existing know- 

 ledge of the composition of most of the sub- 

 stances commonly used as food, would enable 

 us to construct a diet which would be certain 

 to contain an exact proportion of all the 

 necessary salts. For, in the first place, we 

 must recollect the probable importance of 

 some which are only present in very small 

 quantity ; as well as the value that similarly 

 appears to attach to minnte proportions of 

 certain organic acids, and their compounds 

 with bases. In the next place, we must re- 

 member that, both in animals and vegetables, 

 these taline constituents seem liable to vary, 

 in nature as well as amount, according to the 

 peculiarities of the soil from which they are 

 ultimately derived. It is not by any means 

 easy to insure their presence. And a good 

 scale of diet ought to provide against any 

 danger of their deficiency, by adding so 

 much of various fresh vegetables as would 

 cover all possibilities of such an occurrence. 

 Indeed, nothing short of such variety would 

 make the saline quality of any food perfect. 



A similar argument will apply to the quan- 

 tities of all the other ingredients. The mecha- 

 nical state of the protein and hydrate of carbon 

 will have at least as much influence in deter- 

 mining their requisite amount as the quantity 

 rendered necessary by the waste of the tissues. 

 Hence, to this latter estimate we have always 

 to add a large excess ; such as will be sufficient 

 to cover the surplus protein which passes, 



