STIMULA TION OF THE S YMPA THE TIC NER VE, 497 



sympathetic saliva may be obtained. It is convenient to have some 

 name for this unusually rapid sympathetic secretion, and I have called 

 it the augmented secretion)- 



In the dog, the saliva of the augmented secretion is, in its physical 

 characters and apparently in its percentage composition, intermediate 

 between sympathetic saliva and that obtained by stimulating the 

 cranial nerve. 



The augmented sympathetic saliva from the submaxillary gland of 

 the dog is three to ten times as abundant as ordinary sympathetic, 

 saliva. In fifteen seconds about \ c.c. is usually secreted, but there 

 may be as much at J c.c. The amount of the augmented secretion from 

 the parotid is one-third to one-half that of the submaxillary gland. 



The augmenting effect of stimulating the cranial nerve disappears 

 in time, although the sympathetic is not stimulated in the interval. 

 In the submaxillary gland of the dog the greater part of the effect dis- 

 appears in ten to fifteen minutes. In the parotid, it has usually com- 

 pletely disappeared in ten minutes. The rate of disappearance does not 

 seem to be affected by the injection of atropine. 



Mere vascular dilation does not cause an augmented secretion, for 

 if atropine be given in sufficient quantity, to paralyse completely the 

 cranial secretory nerves, stimulation of the cranial nerve, which still 

 gives largely increased blood flow, does not increase to any considerable 

 extent the sympathetic saliva obtained subsequently. 



When the sympathetic nerve is stimulated two or three times in 

 succession for rather short periods, say of thirty seconds, the augmenting 

 effect of a preceding cranial nerve stimulation does not necessarily cease 

 with the first stimulation, but is visible, though to a much less degree, in 

 the second, and it may be in later stimulations. In the case of the dog's 

 parotid the third stimulation usually gives no secretion at all. 



The following extracts from the notes of experiments will illustrate the 

 statements made above with regard to the augmented secretion : 



Submaxillary Gland Dog Stimulation of the Sympathetic after moderate 

 Stimulation of the Chorda Tympani. 



Saliva secreted in mm. during 



successive 30 sees., 35^ mm. 



= 25 c.c li 1J 1 1 53^ 20 1 20 4 2 1 



Nerve stimulated . . . Sy. Cli. Sy. 



In the second sympathetic stimulation the flow of saliva was 16 mm. 

 during the first fifteen seconds, and 4 mm. during the second fifteen seconds. 



Submaxillary Gland Dog Stimulation of the Sympathetic after brief 

 Stimulation of the Chorda Tympani. 



Saliva flow every 



30 sees, in mm. 0510 15 1000 Hi 



Nerve stimulated Ch. Sy. Sy. 



(for 2 to 3 sees.) 



Longer stimulation of the chorda tympani has little effect upon the 

 maximum rate of flow of the augmented secretion, but it leads apparently to a 

 less rapid fall after the maximum is attained. 



1 Journ. Physiol., Cambridge and London, 1889, vol. x. p. 291. 

 VOL. I. 32 



