QUANTITY OF SALIVA. 



through the mouth. It is well known that the quantity of 

 saliva may be increased by directing the attention to this 

 secretion, moving the tongue about in the mouth, sucking 

 the cheeks, and discharging the fluid by sputation ; and it 

 may be largely increased by taking into the mouth glass 

 beads, pebbles, or smooth articles of this kind. 



Quantity of Saliva. It is not easy to estimate, in the 

 human subject, the entire quantity of saliva secreted in the 

 twenty-four hours ; and great variations in this regard un- 

 doubtedly exist in different persons, and even in the same 

 individual at different times. An approximate estimate may 

 be arrived at by noting, as nearly as possible, the average 

 quantity secreted during the intervals of digestion, and add- 

 ing to it the quantity absorbed by the various articles of food. 

 Some of the earlier physiologists investigated this subject 

 with much patience. Berard quotes the experiments of Sie- 

 bold, who collected the saliva by holding the mouth open 

 with the head inclined so that the fluid should flow into a 

 vessel as fast as secreted. 1 An estimate of this kind can only 

 be approximative ; and those made by Dalton are apparently 

 the most satisfactory. This observer found that he was able 

 to collect from the mouth, without any artificial stimulus, 

 about five hundred and fifty-six grains of saliva per hour ; 

 and he also found that wheaten bread gained in mastication 

 fifty-five per cent., and lean meat forty-eight per cent, in 

 weight. Assuming the daily allowance of bread to be nine- 

 teen ounces, and the allowance of meat to be sixteen ounces, 

 and estimating the quantity of saliva secreted during twenty- 

 two hours of interval, the entire quantity in twenty-four hours 

 would amount to 20,164 grains, or a little less than three 

 pounds avoirdupois, of which rather more than one-half is 

 secreted during the intervals of eating. 2 



Remembering that the quantity of saliva must necessarily 



1 Op. cit., tome i., p. 696. 



2 DALTON, A Treatise on Human Physiology, Philadelphia, 1864, p. 128. 



