134 PHYSIOLOGY. 



hunger and thirst is not known. In all cases, it is acknowledged that 

 thirst is more painful than hunger., and it is more urgent to satisfy 

 thirst than hunger. A dog without fo6d, but supplied with water, 

 lives twice as long as a dog deprived of both food and water. 



Pharmacological. 



Potassium chlorate is excreted in the saliva. 



Fat and bismuth restrain the flow of gastric juice. 



Morphia stops the movements of the stomach and food remains 

 there a long time. 



Sulphur produces peristalsis by the development of sulphuretted 

 hydrogen, which acts as a chemical stimulant. 



Emetine of ipecac acts directly on the vomiting center, and also 

 on the vagus nerve-ends in the stomach. 



Tea is not favorable to digestion, as it retards the action of 

 ptyalin. In the majority of cases of dyspepsia ptyalin is diminished. 



In emotions, when the mouth becomes dry, it is caused by a 

 psychical effect on the sympathetic. 



The acid of the gastric juice seems to have but little control 

 over the prevention of putrefaction, hence the diarrhoea of achylia is 

 not due to an increase of putrefactive changes. Cold drinks are apt 

 to escape from the stomach not thoroughly warmed, and may be a 

 cause of diarrhoea. 



After the age of fifty, Scidelin states that 40 per cent, have 

 little or no HCL. 



When more hydrochloric acid is required it is obtained by aug- 

 menting the whole quantity of gastric juice, which is pretty constant 

 in its chemical contents, and not by pouring out a more acid juice. 



Colic can be caused by a want of co-ordination in peristalsis, 

 where a relaxation in front fails to coincide with a contraction 

 behind. 



