SECRETION OF SALIVA AND GASTRIC JUICE. 



271 



FIG. 85. 



little secretion of saliva and in the dog to none at all, a marked effect on 

 the gland is produced, and changes in the same direction as those already 

 described may be observed. During rest the cells of the parotid as seen in 

 sections of the gland hardened in alcohol (Fig. 84, A) are pale, transpa- 

 rent, staining with difficulty, and the nuclei possess irregular outlines as if 

 shrunken by the reagents employed. After stimulation of the sympathetic 

 the protoplasm of the cells becomes turbid (Fig. 84, B), and stains much 

 more readily, while the nuclei are no longer irregular in outline, but round 

 and large, with conspicuous nucleoli, the whole cell at the same time, at 

 least after prolonged stimulation, becoming distinctly smaller. 



f205. In a mucous gland the changes which take place are of a like 

 , though apparently somewhat more complicated, owing probably to 

 the peculiar characters of the mucin which is so conspicuous a constituent 

 of the secretion. 



If a piece of resting loaded submaxillary gland be teased out, while 

 fresh and warm from the body, in normal saline solution, the cell-substance 

 of the mucous cells (Fig. 85, 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. 85, b\ 

 the granules are far less numerous and largely confined to the part of the 

 cell nearer the lumen, the outer part of the cell around the nucleus consist- 

 ing 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 be- 

 cause the granules do not disappear in so 

 regular a manner as in the pancreas, and 

 partly because the outer zone of the mu- 

 cous 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 pecu- 

 liar nature. If the fresh cell, showing 

 granules (either many as in the case of a 

 loaded or few as in the case of a dis- 

 charged cell), be irrigated with water or 

 with dilute acids or dilute alkalies, the 

 granules swell up (Fig. 85, a', b f , into a 

 transparent mass, giving the reactions of 

 mucin, traversed by a network of " pro- 

 toplasmic " cell-substance. In this way is 

 produced an appearance very similar to 

 that shown in sections of mucous glands 

 hardened and stained in the ordinary 

 way. 



In the loaded mucous cell in hardened 

 and stained preparations (Fig. 86, a) 

 there is seen a small quantity of protoplasmic cell-substance gathered 

 round the nucleus at the outer part of the cell next to the basement mem- 

 brane ; the rest of the cell consists of a network of cell-substance, the in- 

 terstices being filled with transparent material, which, unlike the network 

 itself and the mass of cell-substance round the nucleus, does not stain with 



Mucous Cells from a fresh Subni axil- 

 lary Gland of Dog. (Langley.) a and b 

 isolated in 2 per cent, salt solution: a, 

 from loaded gland; b, from discharged 

 gland (the nuclei are usually more ob- 

 scured by granules than is here repre- 

 sented). On teasing out a fresh fragment 

 in 2 to 5 per cent, salt solution, the cells 

 usually become broken up so that iso- 

 lated cells are rarely obtained entire ; iso- 

 lated cells are common if the gland be 

 left in the body for a day after death ; a', 

 b', treated with dilute acid: a', from 

 loaded ; b'.from discharged gland. 



