DRASTICS AND ASTRINGENTS. 427 



readily induced after purgation, unless the quantity of -water 

 drained off by the bowel have been excessive. 



II. PHARMACODYNAMICS. 



The means of acting physiologically upon the intestine 

 which are at our command are of a much more artificial kind 

 than any we have yet encountered, and introduce us to a large 

 number of medicinal substances. 



1. Food. The influence of the food is felt in the bowels, and 

 affords us a ready means of acting upon them. Many kinds of 

 food increase the action of the bowels, notably coarse, indiges- 

 tible articles of diet, such as the husk of cereals made into 

 "brown bread" and "whole-meal"; green vegetables; oils; 

 fruits, fresh or preserved, which contain abundant salts and 

 sugars ; soups, broths, and other preparations of meat ; eggs ; 

 ale and beer ; tea and coffee, when properly prepared ; and 

 water taken at bed-time, or in the early morning before break- 

 fast. On the contrary, cold articles of food, milk, spirits, red 

 wines, and tea and coffee made strong and badly, are con- 

 stipating in their effects. Perfect digestion in the mouth, 

 stomach, and duodenum, is one of the most powerful means of 

 preserving or restoring the natural action of the bowels. 



We now pass from these natural means of acting upon the 

 bowels, to others of a distinctly medicinal character. 



2. Measures which act upon the intestinal Blood-vessels : 

 Drastics ; Astringents ; Constringents. A number of substances 

 disturb transudation by acting upon the blood-vessels in the 

 intestinal walls. 



a. Drastics. These cause the vessels to dilate, and retard the 

 blood current, so that the fluid and part even of the solid 

 constituents of the blood escape into the walls and cavity of the 

 bowel. In other words, they establish an inflammation of the 

 mucosa, somewhat resembling a common " cold " in the nose. 

 The result is similar in the two cases : there is a profuse 

 discharge from the mucous membrane, of the watery part of 

 the blood, with a certain amount of solid elements, constituting 

 a " catarrh," and producing in the case of the bowel a very 

 liquid stool. The drugs which act in this way are obviously 

 powerful or even dangerous, and comprise chiefly Croton Oil, 

 Elaterium, Gamboge, and Colocynth. They constitute a group of 

 purgatives known as drastics (Spdca, I act) or drastic cathartics. 



b. Intestinal Astringents. Opposed to these measures we 

 possess certain substances which contract the walls of the 

 intestinal vessels, reduce the quantity of watery exudation, pre- 

 vent the escape of solid elements, and thus diminish the liquidity 

 of the faeces. Such substances, include Lead, Silver, and the 



