28 ' CHORDA '-SUBMAXILLARY SALIVA. [BOOK II. 



Analyses I. and III. were of saliva obtained by stimulating the 

 mouth with vinegar; II. of saliva which flowed spontaneously imme- 

 diately after the fistula had been established, and IV. of saliva poured 

 out during mastication. 



inorganic The soluble salts consist mainly of sodium chloride 



salts i of sub- an( j SO( Ji um carbonate; the insoluble, of calcium car- 

 saitva ary bonate and phosphate. 



Characters of Submaxillary Saliva secreted on stimulation of the 

 Chorda Tympani. 



When the chorda tympani is stimulated there is obtained an 

 abundant flow of submaxillary saliva possessing its normal fluidity. 

 At the same time there occur changes in the circulation in the gland 

 which do not specially concern us, and a rise in temperature which 

 may according to Lud wig's determination amount to 1*5 C. This 

 secretion on stimulation of the chorda may be provoked even when 

 the circulation has ceased ; for example, in the gland of a decapitated 

 head. Heidenhain has shewn that, although ' chorda-saliva ' is, as 

 was before known, poor in organic solids as compared with the saliva 

 which flows on stimulation of the sympathetic filaments, yet the 

 secretion varies with the intensity of the stimulus. 



The amount of saliva secreted augments perceptibly 



Influ nceo * as the stimulation of the chorda increases in intensity. 



stimulus on ' ^ the same time, the salts of the saliva increase very 



amount of se- materially, until their proportion attains 0'5 0'6 p. c. 



cretion and The proportion of salts always increases with the 



proportion of water secreted. This result is obtained 



constituents 6 whatever the time at which the stimulation has been 



commenced, even if secretion has been going on for hours. 



Langley and Fletcher from an extended investigation on the sub- 

 ject have arrived at the conclusion that ' the secretion of organic 

 substance depends wholly, or almost luholly, upon the strength of the 

 stimidus, whilst the secretion of water and of salts depends also upon 

 the amount of blood flowing through the gland 1 ! 



As the amount of organic constituents secreted in the saliva 

 depends intimately upon the store of matters which the secreting 

 cells contain, it follows that the amount of organic matters secreted 

 upon stimulation will depend very greatly upon the work which 

 the gland has previously done. 



If the chorda tympani be stimulated when the submaxillary 

 gland has been in repose, it is noticed that on increasing the 

 strength of the stimulus there is increase not only in the amount 



1 J. N. Langley and H. M. Fletcher, 'On the Secretion of Saliva, chiefly on the 

 Secretion of Salts in it.' Phil. Transact. Vol. 180 (1889), B, p. 132. 



