CHAP, i.] TISSUES AND MECHANISMS OF DIGESTION. 409 



cell-substance of the mucous cells (Fig. 66 a) is seen to be crowded 

 with granules or spherules which may fairly be compared with the 

 granules of the pancreas, though perhaps less dense and solid than 

 these. 



If a piece of a gland which has been secreting for some time, 

 and is therefore a discharged gland, be examined in the same way 

 (Fig. 66 b) the granules are far less numerous and largely confined 



FIG. 66. Mucous CELLS FKOM A FRESH SUBMAXILLARY GLAND OF DOG. (Langley.) 



a and b isolated in 2 p.c. salt solution : a, from loaded gland, b from discharged 

 gland (the nuclei are usually more obscured by granules than is here repre- 

 sented). 



(On teasing out a fragment of fresh in 2 to 5 p.c. salt solution, the cells usually 

 become broken up so that isolated cells are rarely obtained entire ; isolated 

 cells are common if the gland be left in the body for a day after death. ) 



a', &', treated with dilute acid : a' from loaded, b' from discharged gland. 



to the part of the cell nearer the lumen, the outer part of the cell 

 around the nucleus consisting of ordinary ' protoplasmic ' cell- 

 substance. The distinction however between an inner 'granular 

 zone ' next to the lumen and an outer ' clear zone ' next to the 

 basement membrane is less distinct than in the pancreas, partly 

 because the granules do not disappear in so regular a manner as in 

 the pancreas and partly because the outer zone of the mucous cell, 

 as it forms, is less homogeneous than that of the pancreatic 

 cell. 



The ' granules ' or ' spherules ' of the mucous cell are moreover 

 of a peculiar nature. If the fresh cell, shewing granules, (either 

 many as in the case of a loaded or few as in the case of a discharged 

 cell; be irrigated with water or with dilute acids or dilute alkalis 

 the granules swell up (Fig. 66 a, b') into a transparent mass, giving 

 the reactions of mucin, traversed by a network of ' protoplasmic ' 

 cell-substance. In this way is produced an appearance very similar 

 to that shewn in sections of mucous glands hardened and stained 

 in the ordinary way. 



