100 SIALAGOGUES 



other substances moved in the mouth, by irritation of the 

 stomach, or even of the nostrils, stimulation is conveyed by 

 their respective nerves to these ganglia, and reflexly saliva- 

 tion ensues. In this way the presence of food in the mouth 

 and the movements of the jaws naturally provoke saliva- 

 tion. In like manner, through nerves of taste, distributed 

 within the mouth, acids, alkalies, bitters, ethers, mustard, 

 ginger, and other pungent substances reflexly increase 

 secretion of saliva. Tartar emetic, and in fact all emetics, 

 exert similar effects reflexly by acting on the stomach. 

 Jaborandi, calabar bean, and their alkaloids, with muscarine 

 and nicotine, produce salivation when injected into the blood 

 by stimulating the peripheral ends of the secreting nerves 

 within the glands or nerve-cells in the ganglia, and are 

 termed specific sialagogues. Another group, including 

 mercury, and potassium iodide, induce their effects by 

 stimulating the gland cells, to a slight extent, during 

 excretion. 



The salivary and buccal secretions moisten the mouth and 

 fauces, and hence facilitate mastication and swallowing, and 

 lessen or prevent thirst. The ptyalin of the saliva, more- 

 over, helps the digestion of starch in the stomach, whilst 

 still the secretion of gastric juice is small. Graminivora 

 secrete proportionally large quantities of saliva for the 

 moistening of the dry food, on which they chiefly live. The 

 horse in twenty-four hours secretes 84 Ibs. In all animals 

 the fluid is more alkaline the larger the amount of the 

 starch food. 



Antisialics are medicines which lessen the salivary secre- 

 tion. Borax and potassium chlorate frequently remove the 

 faulty irritable conditions of the mucous membrane, which 

 lead to over-secretion. Opium and morphine diminish irri- 

 tability of the nerve-centres, while atropine is the most 

 effective paralyser of the peripheral endings of secreting 

 nerves. The fermentative action of ptyalin is diminished 

 by alcohol, alkalies, and acids, and checked by 1 per cent, 

 solution of carbolic acid. 



Refrigerants, in contact with the buccal and pharyngeal 

 membrane, induce a sensation of coolness, and allay thirst, 

 which is locally manifested by dryness of the mouth and 



