FUNCTIONS OF THE SALIVARY GLANDS. 271 



former may be ascribed the role of motor nerve, which conveys 

 impulse-waves that incite the gland to activity and govern the 

 latter, while the part of vasodilator would be fulfilled by the 

 vascular fibers. "We thus require nothing more to complete 

 the gland's functional mechanism. 



Still, it is difficult to concede that the copious supply of 

 sympathetic fibers along the branches of the facial and lingual 

 that penetrate the organ should hold no place in the active 

 process, since their exclusion as efferent nerves simultaneously 

 eliminates them from the latter. If their influence on the 

 parotid gland can be taken as a standard, however, whatever 

 part they play, though perhaps not directly connected with 

 active function, must be directly concerned with the structural 

 integrity of the organ. Thus, Onuf and Collins state that 

 "when the parotid gland is thrown into an intense activity by 

 the cerebral secretory nerve so that it secretes from twelve 

 to thirteen cubic centimeters of saliva, the secretion scarcely 

 differs in its microscopical appearance from that of the gland 

 in a state of rest. If, on the other hand, it has secreted from 

 two to three cubic centimeters of saliva under the influence 

 of the sympathetic nerve, the character of the cells is changed 

 to such a degree that one thinks he has to deal with a com- 

 pletely new organ." They also refer to the experiments of von 

 Wittich, which showed that "excitation of the cervical sym- 

 pathetic nerve remained without effect upon the secretion of the 

 parotid gland, if the facial nerve of the same side had been 

 torn out from the cranial cavity either immediately or some 

 days before." All this suggests that the sympathetic fibers, 

 as is probably the case with the lacrymal glands, are not dis- 

 tributed directly to the glandular elements: a view empha- 

 sized by the experimental observations of Heidenhain, which 

 showed that the secretion obtained by excitation of the sym- 

 pathetic nerve (in dogs or rabbits) was very scarce. That 

 similar experiments would be followed by corresponding results 

 in the case of the submaxillary glands is very probable, inas- 

 much as their functions, nervous and vascular supply, and 

 general histological structure are similar to those of the 

 parotids. 



Foster's belief that the chorda tympani is practically the 



