It is interesting to note that he also found a complete absence of any trace of secondary depression or of any sort of secondary reaction consequent upon the stimulation which was so strikingly present in many of the tests. The production of an increased capacity for work was clearly demonstrated, the same being a genuine drug effect, and not merely the effect of excitement, interest, sensory stimulation, expectation, or suggestion. However, this study does not show whether this increased capacity comes from a new supply of energy introduced or rendered available by the drug action, or whether energy already available comes to be employed more effectively, or whether fatigue sensations are weakened and the individual's standard of performance thereby raised. But they do show that from a standpoint of mental and productive physical efficiency "the widespread consumption of caffeinic beverages, even under circumstances in which and by individuals for whom the use of other drugs is stringently prohibited or decried, is justified." _Conclusion_ Brief summarization of the information available on the pharmacology of coffee indicates that it should be used in moderation, particularly by children, the permissible quantity varying with the individual and ascertainable only through personal observation. Used in moderation, it will prove a valuable stimulant increasing personal efficiency in mental and physical labor. Its action in the alimentary regime is that of an adjuvant food, aiding digestion, favoring increased flow of the digestive juices, promoting intestinal peristalsis, and not tanning any portion of the digestive organs. It reacts on the kidneys as a diuretic, and increases the excretion of uric acid, which, however, is not to be taken as evidence that it is harmful in gout. Coffee has been indicated as a specific for various diseases, its functions therein being the raising and sustaining of low vitalities. Its effect upon longevity is virtually _nil_. A small proportion of humans who are very nervous may find coffee undesirable; but sensible consumption of coffee by the average, normal, non-neurasthenic person will not prove harmful but beneficial. [Illustration] CHAPTER XIX THE COMMERCIAL COFFEES OF THE WORLD _The geographical distribution of the coffees grown in North America, Central America, South America, the West India Islands, Asia, Africa, the Pacific Islands, and the East Indies--A statistical study of the distribution of the principal kinds--A commercial coffee chart of the world's leading growths, with market names and general trade characteristics_