486 LECTURE XXI. 



If the lingual nerve, which carries the cerebral fibers to the sub- 

 maxillary gland, is cut, and then the peripheral stump stimulated, the 

 blood-vessels in the gland become dilated. The blood streams from the 

 veins with a bright red color similar to that of the arterial blood. At the 

 same time there is an increased secretion of saliva. On the other hand, 

 by stimulating the fibers of the sympatheticus, the blood-vessels are con- 

 tracted. The blood passes more slowly, and the flow from the veins is 

 small in amount and of a dark blue color. The activity of the secretion 

 is diminished. 1 That, on the other hand, the innervation of the blood- 

 vessels is not the sole function of the above-mentioned nerves, is shown 

 by the experiments of Heidenhain. 2 He found that with the lingual nerve 

 two kinds of nerve fibers enter the gland. If a dog was poisoned with 

 atropin, then stimulation of the facial nerve fibers caused as before an 

 acceleration of the blood-stream, while, on the other hand, there was no 

 increase in the secretion of saliva. From this it is clear that the facial 

 nerve, as well as the sympathetic, carries fibers to the submaxillary gland 

 which have a specific action upon the individual cells of the gland. For 

 the present we know but little concerning the details by which this stim- 

 ulation is effected. It has not yet been found possible to establish 

 beyond reasonable doubt the anatomical relations of the nerve fibers to 

 the cells of the gland. 



C. Ludwig and A. Spiess 3 have shown that with the activity of the cells 

 the temperature also rises. They introduced a thermometer in the large 

 vein of the submaxillary gland of a dog, a second in the exit duct from this 

 gland, and a third in the carotid artery. If now the facial fibers were 

 stimulated, then from the time of beginning of the activity of the glands 

 the thermometers in the saliva and in the vein registered higher tempera- 

 tures than that of the carotid. 



It was at one time believed that the formation of the saliva could be 

 regarded as a filtration process. It was soon found, however, that the 

 separation of this liquid was evidently due to a specific activity on the part 

 of the gland-cells. Even the chemical composition of the saliva indicates 

 this. It is entirely different from the blood and lymph, and must have been 

 formed only by means of a specific choice of the individual constituents 

 of these liquids on the part of the gland-cells. In fact, it is even necessary 

 for these last to produce for themselves certain substances. Here, we 

 cannot treat in detail of all the evidence which has been brought forward 

 against the assumption that the separating of the saliva is a result of a 

 filtration process. We can only briefly touch upon it. Thus it has 



1 Claude Bernard: Compt. rend. 47, 245 (1858). 



2 Pfliiger's Arch. 5, 309 (1872); 17 (1878). See also Barbara: Bull, scienze med. 

 di Bologna (8), 2, 1 (1902). 



3 Sitzber. Wiener Akad. 25, 548 (1857). 



