.1885.] 



The " Paralytic " Secretion of Saliva. 



215 



changes occurring locally, is affected by dyspnoea, by apncea, and 

 by anaesthetics in the same way as it is when produced by nervous 

 impulses sent out from the central secretory centre ; and this strongly 

 suggests that the secretion in the former case also is brought about 

 by nervous impulses, proceeding in this instance from a local secretory 

 centre. 



I conclude, then, that section of the chorda tympani causes an in- 

 crease in irritability, both in a central and in a local secretory centre, 

 during which increase of irritability the blood passing through the 

 centre serves as an effective stimulus. The central centre in no very 

 long time recovers its normal state, the local centre does not. Pro- 

 bably it and the gland eventually atrophy unless the chorda tympani 

 regrows. 



Although the secreting cells of the sub-maxillary gland steadily 

 diminish in size during the paralytic secretion, they undergo only 

 slight histological changes ; they become somewhat more mucous. The 

 demilune cells and the serous cells, which are present in considerable 

 number in the sub -maxillary gland of the cat, do not show any 

 obvious change, except their diminution in size ; the increase in the 

 number of these cells, which is stated by Heidenhain to occur, I have 

 not observed. That the cells, in spite of the paralytic secretion, are 

 in a "resting" and not in an " active " condition, is further shown by 

 the cells being, in the fresh state, granular throughout. On the side 

 of the antilytic secretion the gland-cells are rather less mucous than 

 in the normal " resting " gland. 



