BY DR. LAUDER BRUNTON. 467 



felt. Exactly on a level with this depression, and in a line 

 with the insertion of the zj'gomatic arch, make an incision 

 through the skin, cutting obliquely in a direction from the 

 inner canthus of the eye towards the angle of the mouth. On 

 dividing the subcutaneous cellular tissue, the facial vein and 

 artery, a nerve, and the parotid duct will be found all together. 

 The duct lies most deeply and runs from behind forwards, 

 while the artery, with its accompanying vein, pass from above 

 downwards. It is of a pearly white color. Isolate it, and 

 divide it as near the mouth as possible. The wound must be 

 closed round the duct, and the duct secured in it by a suture, 

 just as in the case of the submaxillary gland. 



* 90. Effect of Stimuli on Secretion. In animals with 

 permanent fistuke, whether parotid or submaxillary, it can be 

 demonstrated that these glands do not secrete excepting when 

 secretion is excited by stimulants. The stimulation may con- 

 sist in the introduction into the mouth of sapid substances, 

 such as vinegar (which, in common with acid substances in 

 general, acts most on the parotid), quinine, or colocynth, or 

 of ether, or in electrical excitation of the tongue. The action 

 of mental stimuli may be also shown, as, e. g., by placing a bone 

 before the nose of a fasting dog without allowing him to reach 

 it. From Schiff's experiments, it appears that this kind of 

 stimulation has no effect on either the parotid or submaxillary. 

 The mastication of a bone produces an abundant secretion from 

 both glands, but mastication of a tasteless substance, as, e. g., 

 a piece of wood, has no effect on the parotid, 'and a very slight 

 one on the submaxillary. For rabbits a piece of hard biscuit 

 should be used in place of a bone. 



EXPERIMENTAL INVESTIGATION OF THE FUNCTIONS OP THE 

 SUBMAXILLARY GLAND. 



91. Owing to its comparatively exposed position, the sub- 

 maxillary gland has been more completely studied than either 

 of the other two. The investigation of its functions has yielded 

 results which have acquired an importance far beyond that 

 which they possess as bearing on the secretion of saliva. They 

 form, indeed, the basis of all that is known as to the nature of 

 glandular action, and of the influence exercised on it by the 

 nervous system. Before proceeding to describe the methods 

 eniplo}*ed, it will be necessary to give a short account of its 

 anatomical relations, and particularly of the bloodvessels and 

 nerves which are distributed to it. 



Nerves. The gland receives nerve fibres from three sources, 

 viz., from the facial, from the submaxillary ganglion, and from 

 the cervical sympathetic. The brancn-ofHicTfacial (known as 

 the chorda tympani) reaching the neighborhood of the duct, as 

 part of the trunk of the lingual nerve, leaves that nerve as it 



