Dr. Pfeiffer delivered the second and final lecture on the Chemistry of Digestion before the Boylston Chemical Club in Boylston 9, last night. Dr. Pfeiffer described in his last lecture the various kinds of food-stuffs, and to some extent their course through the body. Last night he dealt with the Processes of Digestion and the Digestive Ferments. Dr. Pfeiffer began by dividing all chemical processes into five factors, as follows: The substance, the apparatus, the reagent, the nature of the reaction, and finally the nature of the products of reaction. These five factors are likewise present in all digestive processes. The substance is in this case the food-stuffs; the apparatus, the mouth, stomach, intestines, etc.; the reagents, the saliva, gastric and pancreatic juices, and the bile; the nature of the reaction, into what state the food-stuff is converted for assimilation; and finally the nature of this digested food-stuff.
At present the conception of these processes is very complex, and although far in advance of the knowledge of our ancestors, we are only at the beginning.
In the process of digestion the food-stuffs are acted upon firstly in the mouth, by the saliva, which not only serves as a lubricant but also to change such carbohydrates, as may be present, into dextrine and sugar. The food is next a +++ted upon in the stomach by the gastric juices, which render the proteids present more soluble and converting them finally into peptone.
In connection with this Dr. Pfeiffer spoke of the perplexing question why the gastric juices did not effect the stomach itself while acting upon all other such substances. Passing on the partly digested food leaves the stomach, having an acid reaction and called chyme. As it enters the intestine, this chyme is attacked by the bile, which serves to neutralize the acid reaction, and further to aid in digesting the fats and oils. Then the pancreatic juice renders the mass fit for the blood to assimilate, and finishes the digestion of the fats and oils.
Although the subject of the lecture did not properly deal with the final assimilation of the digested food, Dr. Pfeiffer showed the process by the aid of a number of charts, showing the internal structure of the intestine, etc. Dr. Pfeiffer concluded his lecture with a number of experiments on the digestive process.