120 OF FOOD, AND THE DIGESTIVE PROCESS. 



dom, appear to contain nearly the same organic constituents, but in different 

 proportions, as shown in the following analysis : 



In making "Tea" and "Coffee," the Theine, Gum, Sugar, and Tannic acids 

 are chiefly extracted, the Casein, unless a little soda be added to. the water, 

 being undissolved. It is a singular circumstance that the Alkaloid con- 

 tained in Tea and Coffee, as well as that in Mate, the shrub used for tea in 

 Paraguay, should have the same chemical composition (C B H IO N 4 O, + 2 Aq.). 

 Strong decoctions of both fluids counteract the tendency to sleep, excite the 

 nervous system and heart, and produce contractions and tremors in the 

 muscles. 1 Tea is a respiratory excitant, while coffee depresses this function. 

 Lehmamr and Bocker 3 consider that tea and coffee diminish the excretion 

 of urea, and consequently the disintegration of the albuminous tissues, whilst 

 they effect an increase in the amount of water discharged. Voit, 4 however, 

 from observations on a dog, and Squarey, 5 from experiments on men, con- 

 clude that coffee possesses little or no influence on the general nutrition of 

 the body. 



2. Of Hunger and Thirst Starvation. 



74. The want of solid Aliment, arising from the demands of the system 

 for the materials requisite for the growth and maintenance of the body, and 

 for the combustive process, is indicated by the sensation of Hunger; and 

 that of liquid, by Thirst, The former of these sensations is referred to the 

 stomach, and the latter to the fauces; but although certain conditions of 

 these parts may be the immediate cause of the sensations in question, they 

 are really indicative of the requirements of the system at large. For the 

 intensity of the feeling bears no constant relation to the amount of solid or 

 liquid aliment in the stomach ; whilst, on the other hand, it does correspond 

 with the excess of demand in the system, over the supply afforded by the 

 blood ; and it is caused to abate by the introduction of the requisite material 

 into the circulating fluid, even though this be not accomplished in the usual 

 manner by the iugestion of food or drink into the stomach. 



75. That the sense of hunger, however, is iiniiit'iiinh'/;/ dependent upon 

 some condition of the Stomach, seems to follow from the fact, that it may be 

 temporarily alleviated by introducing into the digestive cavity matter which 

 is not alimentary. Of the precise nature of that condition, we have no cer- 



1 See M. Levcn in Brown-S6quard's Archives de Physiologic, t. i, p. 170. 



2 Lieliig's Aniinlcn, B;md Ixxxvi, p '205. 



3 Arcliiv d. Vcreins f. geim-ins, 1853. 



4 Hcnlc and .Mrissm-r's IJ^ridii , ISii'i. p . 402. See also H. Aubert, Pfliiger's 

 Arcliiv f. riiysinlogj,., 15,1ml v, 1872. p ',S'.i. 



6 See Dr. Parkin's Practical Hygiene, 4th edit., p. 287. 



