1885.] 



The "Paralytic" Secretion of Saliva. 



213 



paralytic secretion is stopped for several hours at least, by cutting 

 the sympathetic nerve-fibres running to the gland ; the antilytic 

 secretion is made slower by cutting the chorda tympani, and is 

 stopped by cutting, in addition, the sympathetic fibres on the carotid, 

 that is, the secretion ceases in each case when the nervous connexions 

 between the gland and the central nervous system are severed. 

 From this it follows that the paralytic secretion in its early stage is 

 caused by nervous impulses passing from the central secretory centre 

 down the sympathetic nerve to the gland, and that the antilytic 

 secretion is similarly caused by nervous impulses sent out from the 

 central secretory centre, but passing in part down the chorda tympani 

 nerve which is here intact. 



Since the paralytic secretion is more copious than the antilytic 

 secretion, it follows that the nervous impulses sent out by the secre- 

 tory centre on the side of the body on which the chorda tympani is 

 cut, are of greater intensity than those sent out by the secretory 

 centre of the opposite side. Thus, section of one chorda tympani is 

 followed by a change in the central secretory centre of such a nature, 

 that it continuously sends out nerve-impulses tending to produce a 

 secretion from the sub-maxillary glands ; the change, however, is not 

 equal on the two sides, but is more profound on the side of the body 

 on which the chorda tympani has been cut. 



That the central nerve-cells concerned in producing the secretion 

 are not in their normal condition, can be shown in another way. It 

 is well known that in a normal animal, dyspnoea causes, when the 

 chorda tympani nerve is intact, a secretion of saliva from the sub- 

 maxillary gland. Now, in the stage of the paralytic and antilytic 

 secretion spoken of above, when they are produced by stimuli sent 

 out by the central nervous system, dyspnoea causes a much more rapid 

 flow of saliva, and causes it sooner than it does normally; moreover, 

 the effect of dyspnoea is greater on the paralytic than on the anti- 

 lytic secretion. Hence, then, section of one chorda tympani causes 

 an increase of irritability in the central secretory centre, the increase 

 of irritability being greater on the side of the body on which the 

 chorda tympani nerve has been cut. 



Since a venosity of blood greater than normal, will, in a normal 

 animal, serve as a stimulus to the central nerve-cells, and cause a flow 

 of saliva, it is probable that if the irritability of the nerve-cells be in- 

 creased, the normal venosity of the blood will serve as a stimulus to 

 the nerve-cells, and cause a flow of saliva. Hence I think it is not 

 unreasonable to suppose that the paralytic and the antilytic secretions 

 in their early stages are essentially similar to the dyspnoea secretion 

 of the normal animal, and that they are proximately caused by the 

 central nerve-cells, in their state of increased irritability, being 

 stimulated by the blood supplied to them. This view is confirmed by 



