6 CHEMICAL PHYSIOLOGY. 



branes of the cavity of the mouth, constitutes mixed 

 saliva. This can be collected in quantity by irritating 

 the fauces with a feather, and producing vomituritions. 

 It does not reduce alkaline copper solution, but retains 

 a little copper oxyde in solution when cupric salt and 

 alkali only are added. It transforms starch into sugar, 

 so that chewed pap after some standing, with cupric 

 sulphate and caustic potash, at 70 C, yields red copper 

 suboxyde. It does not change cane-sugar into invert 

 sugar, and thus differs from yeast. The quantity of 

 mixed saliva secreted by a man in 24 hours varies 

 between 300 and 1500 grammes ; it may be greatly 

 increased by excitants, and irritating medicines and 

 poisons. 



sai^a in dia- Little is known of saliva in disease, but the investiga- 

 tions of the future promise further results. In diseases, 



Anomalous , . . n 



ingredients, such as salivation under the innuence ot mercury, 

 rhodanates disappear. The saliva then contains mercury. 

 Many medicinal salts pass easily into the saliva from the 

 blood, such as iodide and chlorate of potassium, and 

 when used long in quantity produce slight salivation. 

 In diabetes the saliva contains lactates, but no sugar. 

 In the paralytic saliva of hysteric persons leucine has 

 been found. Acid saliva seems to contain lactic acid, 

 and is of course anomalous. The presence of urea has 

 been alleged, but not proved with certainty. In 

 hydrophobia the saliva is the bearer of the contact- 

 poison by which the disease is propagated to other 

 individuals. 



Digestion of While the saliva influences starch as indicated, and 



starch. 



does not lose its action by the admixture of acid of 



