434 CHANGES IN MUCOUS CELLS. [BOOK n. 



small quantity of protoplasmic cell-substance gathered round the 

 nucleus at the outer part of the cell next to the basement 



a 



FIG. 67. ALVEOLI OF DOG'S SUBMAXILLARY GLAND HARDENED IN ALCOHOL AND 

 STAINED WITH CARMINE. (Langley.) (The network is diagrammatic.) 



a, from a loaded gland. 



6, from a discharged gland ; the chorda tympani having been stimulated at short 

 intervals during five hours. 



membrane; the rest of the cell consists of a network of cell- 

 substance, the interstices being filled with transparent material, 

 which, unlike the network itself and the mass of cell-substance 

 round the nucleus, does not stain with carmine or with certain 

 other dyes. The discharged cell in similar preparations (Fig. 67 b) 

 differs from the loaded cell in the amount of transparent non- 

 staining material being much less and chiefly confined to the 

 inner part of the cell, while the protoplasmic cell-substance around 

 the now large and well-formed nucleus is not only, both relatively 

 and absolutely, greater in amount, but stains still more deeply 

 than in the loaded cell. 



It would appear therefore that in the mucous cell, as in the 

 pancreatic cell, the cell-substance forms and deposits in itself 

 certain material in the form of granules. During secretion these 

 granules disappear and presumably form part of the secretion. 

 But the granules of a mucous cell differ from those of the 

 pancreatic cell inasmuch as they are apt under the influence 

 of reagents to be transformed, while still within the cell, into 

 the transparent viscid material which we call mucin ; hence the 

 appearances presented by sections of hardened glands. It seems 

 natural to infer that the granules consist not of mucin itself 

 but of a forerunner of mucin, of some substance which can give 

 rise to mucin, and which we might call mucigen. And we might 

 further infer that during the act of secretion the granules of 



