380 



Mr. J. N. Langley on the Structure of [Nov. 27, 



drop or two ; lie found, nevertheless, that the stimulation caused a 

 marked change in the histological characters of the gland. This I 

 have tried in one dog only ; then stimulation of the sympathetic a 

 little below the superior cervical ganglion caused a flow of saliva, slow 

 indeed, but sufficiently distinct. Stimulation about one minute out of 

 every two to three minutes gave in three hours 1*3 cub. centims. of 

 saliva. This is not a great quantity, but the quality of the saliva was 

 most remarkable, it was a thick jelly ; if the result of successive 

 stimulations were allowed to collect in the cannula, the whole came 

 out in a cohering clot. From time to time, indeed, it was found 

 necessary to clear the duct by squeezing the clotted saliva out of it. 

 The saliva was kindly analysed for me by Mr. Waters, of Christ's 

 College. It contained 8'477 per cent, of solids, of which 7'803 per 

 cent, was organic matter. 



It is possible, though I think very improbable, that in stimulating 

 the sympathetic, Jacobson's nerve was stimulated reflexly, and hence 

 the apparent presence of secretory fibres in the sympathetic. The 

 highest percentage of solids obtained by Heidenhain* by combined 

 stimulation of the sympathetic and Jacobson's nerve was 2'82 percent. 



The gland examined fresh showed a beginning clear zone, often only 

 seen as a thinning of granules at the periphery ; after a larger amount 

 of saliva had subsequently been obtained by pilocarpin injection the 

 clear zone became more marked. 



The Sub -maxillary Gland of the Rabbit. 



In the fresh state this has one very characteristic point, the transition 

 cells are crowded with large conspicuous granules. The outlines of 

 the ductule or transition cells apart from these granules are quite un- 

 recognisable, they appear as patches and bands much darker than the 

 surrounding gland substance. Some of the cells, which from their 

 shape would be called ductule cells, certainly contain similar granules, 

 though they are, I am inclined to believe, absent from the ductule 

 cells, springing immediately from the ducts. The absence of cell out- 

 lines and the difficulty of obtaining thin sections of the fresh gland 

 makes a decision on this point difficult to arrive at. 



The alveoli are clearer than in the parotid ; they contain granules 

 not so refractive and rather smaller than those in the parotid. I have 

 been unable in the animals of varying age with which I have worked 

 to find any constant difference in hunger and digestion, exceptions to 

 what I regard as the rule being all too frequent. The rule is, I think, 

 mainly from experiments on stimulation of the sympathetic and in- 

 jection of pilocarpin, that during secretion the granules disappear 

 from the outer portion of the cells. The exceptions I have spoken of 



* Op. ext., p. 30. 



