CHEMISTRY OF DIGESTION AND NUTRITION. 359 



great. So, also, the long-continued use of alcohol in large quantities is known 

 to produce serious lesions of the stomach, liver, nerves, blood-vessels, and 

 other organs. As has been stated before, alcohol is absorbed easily from the 

 stomach and seems to increase the absorption of other soluble substances. 1 

 Upon the digestive action of the proteolytic and anxiolytic enzymes alcohol 

 in certain strengths has a retarding effect, but in small percentages its action 

 is not noticeable. 2 Upon the secretion of saliva and gastric juice it has a dis- 

 tinct stimulating action, 3 and its action as a general stimulant to the central 

 nervous system is indicated by its effect on the reaction time, and under 

 certain conditions upon muscular exertion as measured by the ergograph. 4 

 The effect of alcohol upon the body evidently varies greatly with the quan- 

 tity used. It may perhaps be said with safety that in small quantities it is 

 beneficial, or at least not injurious, barring the danger of acquiring an alcohol 

 habit, while in large quantities it is directly injurious to various tissues. 



Condiments and Flavors. — These substances probably have a directly bene- 

 ficial effect on the processes of digestion by promoting the secretion of saliva, 

 gastric juice, etc., in addition to the important fact that they increase thepal- 

 atableness of food, and hence increase the desire for food and the secretion 

 of the gastric juice. With reference to the condiments, Brandl has shown 

 that mustard and pepper also markedly increase the absorption of soluble 

 products from the stomach. 



Beef-tea, Meat-extracts. — The recent experiments of Pawlow and his co- 

 workers (see section on Secretion) have shown that these substances have a 

 specific value in their stimulating effect upon the gastric glands. They appear 

 to contain substances that act as definite secretogogues toward these glands. 



Conditions Influencing Body-metabolism. — In considering the influence 

 of the various food-stuffs upon body-metabolism we have for the most part 

 neglected to mention the effect of changes in the condition of the body. It 

 goes without saying that such things as muscular work, sleep, variations in 

 temperature, etc. have or might have an important effect upon the character 

 and amount of the chemical changes going on in the body, and in conse- 

 quence a great many elaborate investigations have been made to ascertain pre- 

 cisely the effect of conditions such as those mentioned upon the amount of 

 the excretions, the production of heat in the body, and other similar points 

 which throw light upon the nature of the metabolic processes. 



Effect of Muscular Work. — It is a matter of common knowledge that mus- 

 cular work increases the amount of food consumed, and then lore the total 

 body-metabolism, but it has been a point in controversy whether the increased 

 oxidations affect the proteid or the non-proteid material. According (<> Liebig, 

 the source of the energy of muscular work lies in the metabolism of the proteid 

 constituents, and with increased muscular work there should be increased de- 



1 Brandl : Zeitschrift fur Biologie, L892, Bd. 29, S. 277. 



2 Chittenden and Mendel : American Journal of the Medical Sciences, 1896. 



:i Chittenden, Mendel and Jackson: American Journal of Physiology, 1898, vol. i. p. 164. 

 4 Schuniberg: Archiv fur Physiologic, 1899, Suppl. Bd. S. 289. 



