CHANGES CONSEQUENT ON FUNCTIONAL ACTIVITY. 457 



a perfectly transparent substance were traversed by numerous 

 extremely fine pale fibrils. These salivary cells, which, on account 

 of their contents consisting in the Dog chiefly of mucus, with 

 but little albumen, Heidenhain has termed " mucous cells," are 

 more or less, though in general but slightly, tinted with carmine. 

 When the staining is more strongly marked, the cells contain 

 albumen. A structure, which is probably the nucleus of the 

 mucous cell, lies together with a little protoplasm at the peri- 

 phery of the alveolus, and resembles the process of the cell in 

 being stained of a deep red colour. Inasmuch as all the pro- 

 cesses, together with the nuclei and protoplasm, are situated at 

 the periphery of the alveolus, a broad red zone is here fre- 

 quently formed. Here and there one or more salivary cells 

 appear more or less deeply tinged with carmine. These cells 

 are named by Heidenhain the " crescent." He regards them 

 as the earlier stages of development of the cells which gradually 

 become " mucous cells," which, I think, is not improbable. He 

 silently acquiesces in the view I have stated above, that all 

 salivary cells do not behave in the same manner with reagents, 

 a difference that I am disposed to attribute to their various 

 grades of development. 



If we now consider the excited gland, the differences which 

 present themselves are, that all the cells are stained with car- 

 mine, though perhaps only slightly, some being more strongly 

 tinted than others the staining, however, independently of the 

 protoplasm, being, on the whole, less marked than in the quies- 

 cent gland ; that no evidences of multiplication by fission of 

 the young cells at the periphery of the alveoli are visible, in 

 corroboration of which I may refer to Plate i., figs. 84 and 85 

 of Heidenhain's Essay ; that all the contour lines are remark- 

 ably pale and softened off, especially those separating the alveoli 

 and the salivary cells, which are no longer defined by thick lines; 

 that the nucleus is less reddened, more delicately contoured, 

 larger, and, generally speaking, spheroidal. The effects of the 

 excitation consequently are, that instead of cells not becoming 

 stained with carmine, with round nuclei shrinking in alcohol, 

 and becoming intensely stained with carmine, we obtain cells 

 reddening with carmine, containing nuclei which undergo no 

 shrivelling in alcohol, and are less deeply stained with carmine. 



