364 



Mr. J. N. Langley. On the [May 13, 



Hence then, when a small amount of fluid only is secreted, the hya- 

 line substance and the granules are turned out of the cells without 

 being completely dissolved, when a certain amount more of fluid is 

 secreted the hyaline substance is completely dissolved, and with still 

 more fluid, the granules also are completely dissolved. Some small 

 fat globules are usually turned out of the cells during secretion. 



According to Heidenhain,* nerve stimulation causes some consti- 

 tuents of the cell to be converted into a more soluble form, this is 

 usually expressed by saying that mucigen is converted into mucin. 

 Apart from the reasons given by Heidenhain, this is probable, since 

 both hyaline substance and granules appear to be more soluble in 

 osmic acid and in chromic acid when they are in saliva than when 

 they are in the gland cells ; but the proof does not seem to me to be 

 conclusive. 



Kleinf has described the mucous cells as being open towards the 

 lumen, in this I am inclined to agree with him ; it is not easy to see 

 in all cells, but in many it is perfectly distinct. 



Although I think that the mucous cells are able to turn out bodily 

 their products, I am unable to agree with the view of Heidenhain^ 

 and of Lavdowsky,§ that the cells disintegrate during secretion. As 

 the decrease in the interfibrillar substance takes place, there is a 

 fresh formation of substance in the outer part of the cells, i.e., as the 

 cell secretes it also grows : the changes which take place are closely 

 comparable to the changes which take place in the pancreas and in 

 other glands, in which there is no question of the disintegration of 

 cells. Moreover, in saliva I can find no evidence of broken down 

 cells ; when the cells of a fresh gland are treated with osmic acid the 

 cell membrane becomes very distinct, when sympathetic saliva is 

 treated with osmic acid no signs of cell membrane are found; nor 

 are nuclei present except those in " salivary corpuscles," which, as 

 stated by Pfliiger,|| are leucocytes. 



Further, there is not, I think, any satisfactory proof that the 

 demilune cells multiply during secretion, and give rise to mucous 

 cells. I have examined glands at various times after stimulation of 

 the chorda and of the sympathetic, and have not, except extremely 

 rarely, found nuclei undergoing indirect division. As I have pre- 

 viously said,^[ I hold the demilunes to be secreting cells of a different 

 nature from that of the mucous cells, for in different glands all 

 variations are found between glands wholly " albuminous " and 



* Zoc cit., p. 108. 



f " Quart. Journ. Micr. Science,** vol. six, p. 151, 1879. 



X Loc. cit. 



§ Max Sc^mlfcze's " Archiv," Bd. xiii, p. 281, 1877. 



|| Strieker's " Histology" (translated by Power), vol. i, p. 454. 



% " Trans. Internat. Med. Congress," 1880. 



