SALIVAEY GLANDS 309 



The nature of the demilunes is the subject of considerable dis- 

 cussion. Haidenhain * first advanced the theory that the mucous 

 cells were destroyed during secretion, and that the function of the 

 demilunes was therefore to replace the disintegrated mucinous 



FIG. 251. FROM THE SUBLINGUAL GLAND OF MAN. 



a, intralobular duct ; <?, acinus whose cells contain no mucus ; s, mucous acini, at s' with 

 a demilune ; sz, mucous cells in the duct, x 500. (After Kolliker.) 



cells. This theory has been practically abandoned, for no one has 

 yet demonstrated active cell division in the demilunes, a process 

 which would necessarily be concomitant with the rapid develop- 

 ment of mucous from demilune cells. 



Hebold f is responsible for the theory, strongly supported by 

 Stohr, that the demilunes represent an inactive, the mucous cells 

 an active phase of mucous secretion. The easy demonstration of 

 intermediate stages in many mucus secreting glands lends strong 

 support to this theory, and in the present state of our knowledge 

 it seems beyond doubt that such a process actually occurs in at 

 least some of the mucus secreting glands. 



A third theory, more recently advanced by Solger \ and stoutly 

 supported by Krause and others, considers the demilunes to be 

 true secreting cells which form a serous secretion and are there- 

 fore functionally independent of the mucinous cells. This theory 



* Arch. f. mik. Anat., 1869. f Bonn, 1879. 



\ Anat. Anz., 1894. Arch. f. mik. Anat., 1895, 1897, and 1901. 



