160 FOODS 



Coffee, Tea, Cocoa, Alcohol, and Tobacco. We defined a food 

 as any substance which when taken into an organism is capable of 

 supplying it with tissue or of producing available energy. Stimulants, 

 on the other hand, technically are agencies that only goad on the vital 

 functions. In practice so-called stimulants partake in some degree of 

 both these characters, excepting tobacco, which has no nutrient prop- 

 erties. Of all the substances of this general class, the above five are 

 those that are in most general use over the world, but it is essential to 

 note that there are many others, of which opium is perhaps the most 

 important. We shall shortly see that of these "stimulants," alcohol is 

 more properly a depressant, while tobacco and alcohol as well are used 

 chiefly because of their preponderant sedative action on the emotional 

 mental processes. 



The importance, good and evil, of these five substances to the human 

 race need not be described. We are in no sense and in no degree con- 

 cerned here with ethics; we take things as we find them, and for scientific 

 purposes state to scientific people the best we can the scientific truth. 

 We, as students of physiology, do not even stop to inquire why many 

 people (most, with one substance or another) so regularly stimulate their" 

 psychophysic organisms. We may note in passing, however, that they 

 do so, and we may be confident that they always will do so despite the 

 hysteria which some, and the wretched warning facts which others, lay 

 before them. From the earliest recorded times and in all lands man has 

 made from various vegetable materials "stimulants" of one sort or 

 another. In the lapse of historic time thus far, say six thousand years, 

 mankind shows no tendency to stop, or to lessen even, the stimulation of 

 his body and mind with these and other products of natural and of human 

 art. In a more enlightened age than ours they may go out of use. 



Coffee has been in use as a stimulant by Europeans about three cen- 

 turies, having been introduced a few years later than tea. It is a decoction 

 of the roasted berry of a shrub, Coffea Arabica, indigenous in Brazil, 

 Arabia, and in many other parts of the world. It contains at least two 

 stimulating elements, an alkaloid of the vegetal-base class, called 

 caffeine (methyl-theobromin or trimethyl xanthin), identical in composi- 

 tion with theine, having a formula C 8 H 10 N 4 O 2 + H 2 O ; and two volatile oils, 

 caffeol (C 8 H 10 O 2 ), source of coffee's aroma and of part of its flavor. Be- 

 sides these, the most important constituent of coffee is caffetannic acid, 

 astringent and inhibitory of hydrolysis in all parts of the alimentary canal. 

 A 1 to 5000 solution of tannin will arrest, for example, the digestive 

 action of ptyalin on starch completely, but it is less inhibitory of pancreatic 

 digestion. As ordinarily made, when it is made well, a cup of coffee 

 contains about 0.13 gram (2 grains) of caffeine and 0.22 gram (3.5 grains) 

 of tannic acid, the amount of volatile oils present being dependent in 

 general terms on the length of the time since the coffee-beans were roasted. 

 The action of caffeine is largely on the nervous system, stimulating it. 

 The mental process is hastened and supported, ennui and fatigue dis- 

 pelled, mental work seeming almost a pleasure far beyond the limits 

 of unstimulated endurance, while its quality is correspondingly improved. 



