DISORDERS OF THE MOUTH. 401 



III. PATHOLOGICAL RELATIONS. 



As has been already suggested, the pathological relations of 

 the mouth and the first part of the digestive process, are of 

 less interest in themselves, for our present purpose, than from 

 their bearing upon digestion in the stomach, and the farther 

 progress of the food. 



1. We discover in the food the chief cause of all digestive 

 disorders, whether it be unsuitable in quality, excessive in 

 quantity, or taken at over frequent or irregular times. 



2. Loss of the sense of taste is familiar in fever, the result 

 being further arrest of the salivary flow, and interference with 

 relish and appetite, always a serious matter in such cases. In this 

 connection must be mentioned the unfortunate tastes of most 

 drugs, the difficulty of their administration, and the degree to 

 which they interfere with the appetite. 



3. Disorders of the secretions of the mouth include chiefly 

 disturbances of the quantity of saliva and mucus. The saliva 

 is probably deficient in some cases of long standing indigestion ; 

 and it is markedly wanting in acute febrile conditions, causing 

 dryness of the tongue and mouth, thirst, loss of relish as we 

 have just seen, and inability to swallow, the morsel being 

 rolled hopelessly about the mouth. A somewhat similar con- 

 dition may be induced by depressing emotions, such as fear or 

 grief ; or by certain medicinal or dietetic substances, including 

 Belladonna, Opium, and Alcohol. Excessive secretion of saliva 

 and mucus (" salivation") was very frequent in the days when 

 Mercury was regularly administered until the "gums were 

 touched " ; and is still occasionally seen from the same cause, as 

 the result chiefly of accident or idiosyncrasy ; or as the effect of 

 Iodine and Iodide of Potassium, under similar circumstances. A 

 reflex salivary flow of a very interesting kind occurs at the 

 commencement of vomiting, and in some cases of gastro- 

 intestinal disorder, constituting one form of " pyrosis " or 

 "water-brash." In other cases salivation is produced by 

 disease of the nervous centres. 



4. Derangements of the excretions of the mouth are among 

 the causes of the "bad taste" and unpleasant odour of 

 the breath, connected with digestive derangements ; the other 

 principal causes of the same being decomposition in the mouth, 

 or excretion by the respiratory passages. Some drugs already 

 mentioned have the same effect, such as Mercury, Iodine, 

 Bromine, and Lead; and the prevention of this unpleasant 

 action may be a difficult task. 



5. Second only to the food itself as a frequent cause of 

 indigestion is the imperfect manner in which the mechanical 



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