64 THE POPULAR SCIENCE MONTHLY. 



To Professor Sir William Roberts, of Manchester, we were already 

 greatly indebted for a series of able and comprehensive researches on 

 the action of " digestive ferments " and the " preparation and use 

 of artificially digested food " ; * to those valuable researches Sir W. 

 Roberts has recently added others equally important, chiefly on the 

 subject of "food accessories" and their influence on the chemical acts 

 of digestion, f 



The results of these experimental inquiries are, in some respects, 

 so novel and unexpected, and they contradict so many apparently un- 

 founded assumptions, that they can not be too soon or too widely 

 known. 



Man, as Sir "W. Roberts begins by pointing out, is a very complex 

 feeder ; he has departed, in the course of his civilization, very widely 

 from the monotonous uniformity of diet observed in animals in the 

 wild state. Not only does he differ from other animals in cooking 

 his food, but he adds to his food a greater or less number of condi- 

 ments for the purpose of increasing its flavor and attractiveness ; but, 

 above and beyond this, the complexity of his food-habits is greatly 

 increased by the custom of partaking in considerable quantity of cer- 

 tain stimulants and restoratives, which have become essential to his 

 social comfort if not to his physical well-being. 



The chief of these are tea, coffee, cocoa, and the various kinds of 

 alcoholic beverages. 



It is to these "food accessories " and the elucidation of their influ- 

 ences on the processes of digestion that Sir TV. Roberts's recent ex- 

 periments and observations have been directed. 



These " generalized food-customs of mankind," he remarks, 



are not to be viewed as random practices adopted to please the palate or gratify 

 our idle or vicious appetite. These customs must be regarded as the outcome of 

 profound instincts, which correspond to important wants of the human econ- 

 omy. They are the fruit of colossal experience, accumulated by countless mill- 

 ions of men through successive generations. They have the same weight and 

 significance as other kindred facts of natural history, and are fitted to yield to 

 observation and study lessons of the highest scientific and practical value. 



It is unnecessary to describe here Sir "W. Roberts's methods of 

 investigation ; they are fully set forth in the volume before us, and 

 they are alike admirable for the ingenuity of their conception and the 

 laborious accuracy of their prosecution. 



His object was to ascertain the precise influence of these food ac- 

 cessories on the three chief parts of the digestive process : 1. Salivary 

 digestion, i. e., the action of the saliva as a digestive agent ; 2. Peptic 

 digestion, i. e., the action of the fluids secreted by the stomach as di- 



* " On the Digestive Ferments and the Preparation and Use of Artificially Digested 

 Food." Lumleian Lectures, delivered before the Royal College of Physicians in 1880 by 

 Sir William Roberts, M. D., F. R. S. London : Smith, Elder, & Co. 



\ " Lectures on Dietetics and Dyspepsia." Smith, Elder, & Co. 



