160 OF FOOD, AND THE DIGESTIVE PROCESS. 



the fistulous opening. Similar disorders of the functions of the stomach 

 result from violent pain in other parts of the body ; the process of digestion 

 in such cases being suspended, and sometimes vomiting excited. When 

 acidulated substances, as food rendered acid by the addition of a little vine- 

 gar, were introduced into the stomach, the quantity of gastric fluid poured 

 out was much smaller, and the digestive process consequently slower, than 

 when similar food, rendered alkaline by a weak solution of carbonate of 

 soda, was introduced. If, however, instead of a weak solution, carbonate 

 of soda in crystal or in powder was introduced into the stomach, a large 

 quantity of mucus and bile, instead of gastric fluid, flowed into the stomach, 

 and vomiting and purging very often followed. When very cold water, or 

 small pieces of ice, were introduced into the stomach, the mucous membrane 

 was at first rendered very pallid ; but soon a kind of reaction followed, the 

 membrane became turgid with blood, and a large quantity of gastric fluid 

 was secreted. If, however, too much ice was employed, the animal appeared 

 ill, and shivered ; and digestion, instead of being rendered more active, was 

 retarded. Moderate heat, applied to the mucous surface of the stomach, 

 appeared to have no particular action on digestion ; but a high degree of 

 heat produced most serious consequences. Thus, the introduction of a little 

 boiling water threw the animal at once into a kind of adynamic state, which 

 was followed by death in three or four hours; the mucous membrane of the 

 stomach was found red and swollen, whilst an abundant exudation of black- 

 ish blood had taken place into the cavity of the organ. Similar injurious 

 effects resulted, in a greater or less degree, from the introduction of other 

 irritants, such as nitrate of silver or ammonia ; the digestive functions being 

 at once abolished, and the mucous surface of the organ rendered highly sen- 

 sitive. 



112. That the quantity of the Gastric Juice secreted from the walls of 

 the stomach depends rather upon the general requirements of the system, 

 than upon the quantity of food introduced into the digestive cavity, is a 

 principle of the highest practical importance, and cannot be too steadily 

 kept in view in Dietetics. A definite proportion only of aliment can be per- 

 fectly digested in a given quantity of the fluid ; the action of which, like 

 other chemical operations, ceases after having been exercised on a fixed and 

 definite amount of matter. The cessation of the action is due, however, not 

 to the pepsin losing its solvent power, since a comparatively minute propor- 

 tion will convert an almost indefinite quantity of albumen or fibrin into 

 peptone, but rather to the presence of a great excess of the dissolved peptone 

 interfering with further action, just as the presence of alcohol or lactic acid 

 in large quantity interferes with those processes of fermentation in which 

 these substances are respectively formed ; in accordance with this, it is found 

 that when the gastric juice is saturated with peptone and ceases to digest, 

 the addition of a little diluted acid will immediately enable it to effect the 

 conversion of a fresh portion of albumen. 1 Nevertheless, the statement of 

 Dr. Beaumont is perfectly true as regards the living subject, that " when 



1 According to Briicke, Pepsin is not destroyed during digestion, but Scbiff main- 

 tains that it is. Briicke, Op. cit., p. 295; Schiff, Op. cit., vol. ii, Le9on xxi. Be- 

 tween two such skilful observers it is difficult to decide. In ;i recent paper on the 

 subject (Cenno sulle Ricerche fntte del Prof. Schiit', etc., abstract in Centnilblatt, 

 1872, p. 788), Schiff states that the stomach of a healthy dog in good physiological 

 condition requires 200 litres (about 4% gallons) of water to develop its full digestive 

 power, and the infusion of the stomach of a large dog in this quantity of water will 

 digest 16'2 Ibs. of albumen ! Bennett (Text-book of Physiology, 1872, p. 203) ob- 

 serves that one part of pepsin dissolved in 60,000 parts of water still possesses a dis- 

 tinct digestive action. 



