30 



' CHORDA '-SUBMAXILLARY SALIVA. 



[BOOK ii. 



The above most interesting facts are explained by tbe hypothesis 

 of Heidenhain, that the chorda tympani contains both secretory 

 fibres that is fibres which influence the proportion of water and of 

 salts secreted and trophic (metabolic) fibres, which influence the 

 discharge of organic constituents from the secreting cell; further, 

 that the latter set of fibres require a more powerful stimulus to excite 

 them than the former ; and lastly, that even though the stimulus be 

 strong, if there be not a supply of available matter in the gland cell 

 the stimulation of the metabolic fibres must remain without effect. 



The influence of fatigue in decreasing the solids, but particularly 

 the organic solids, discharged by the submaxillary gland, on stimula- 

 tion of the chorda tympani, had already been shewn very conclusively 

 by the much earlier experiments by Ludwig and Becker 1 , as may be 

 seen by glancing at the subjoined statement in which the numbers 

 1, 2, 3 and 4 in the first column indicate the order in which the sam- 

 ples were obtained. 



TABLE SHEWING DECREASE OF SOLIDS IN SUBMAXILLARY SALIVA 



OF DOG ON CONTINUED STIMULATION OF THE CHORDA TYMPANI. 



(LUDWIG AND BECKER.) 



In the above experiment a decrease of the organic matters of 

 the saliva under continued stimulation is observed ; in a subsequent 

 experiment by the same authors, it was found that the mineral or 

 inorganic constituents of the saliva exhibited almost as remarkable a 

 diminution, falling from 075 per cent, to 0'48. 



Characters of submaxillary saliva secreted on stimulation of the 

 Cervical Sympathetic. 



Stimulation of the cervical sympathetic, or of the filaments 

 proceeding from this nerve to the submaxillary gland, leads in the 

 dog to a very scanty secretion of alkaline, very viscid and extremely 

 thick saliva, containing a large quantity of solid matter, chiefly 

 mucin. Whilst the specific gravity of submaxillary saliva of the dog, 

 secreted under the influence of stimulation of the lingual nerve, was 



Ludwig and Becker, Zeitschrift f. rat. Med. N. F. 1 (1851), p. 278. 



