340 A MANUAL OF PHYSIOLOGY 



both nerves, since excitation of the sympathetic influences 

 the amount of organic material in the saliva obtained by 

 subsequent stimulation of the chorda, and this organic 

 matter certainly comes, for the most part at least, from 

 substances stored up in the cells. And, indeed, we know 

 nothing of a division of labour between the cells of a gland, 

 except when there are obvious anatomical distinctions. 

 Thus, the submaxillary gland in man contains both serous 

 and mucous acini, and mucin-making cells are scattered 

 over the ducts of most glands, and, indeed, on nearly every 

 surface which is clad with columnar epithelium. In these 

 cases we cannot doubt that one constituent mucin of the 

 entire secretion is manufactured by a portion only of the 

 cells. In the cardiac glands of the stomach, too, the ovoid 

 cells, in all probability, yield the whole of the acid of the 

 gastric juice. But, so far as we know, every hepatic cell is 

 a liver in little. Every cell secretes fully-formed bile ; every 

 cell stores up, or may store up, glycogen. So it is with 

 the secretory alveoli of the pancreas ; one cell is just like 

 another ; all apparently perform the same work ; each is a 

 unicellular pancreas. (But see p. 484.) 



Paralytic Secretion. When the chorda tympani is divided, a 

 slow * paralytic ' secretion from the submaxillary gland begins in a 

 few hours, and continues for a long time accompanied by atrophy 01 

 the gland. There is also a secretion of the same kind from the 

 submaxillary on the opposite side, but it is less copious. This is 

 called the ' antilytic ' secretion, which is most pronounced in the 

 first few days after the operation, and seems to be a transient 

 phenomenon. It can be at once abolished by section both of the 

 chorda and the sympathetic on the corresponding side, and is there- 

 fore due to impulses arising in the central nervous system. The 

 cause of the paralytic secretion has not been fully made out. II 

 within two or three days of division of the chorda the sympathetic 

 on the same side is cut, the secretion is greatly diminished or stops 

 altogether ; and it is concluded that up to this time it is maintained 

 by impulses passing along the sympathetic to the gland from the 

 salivary centre, the excitability of which has been in some way in- 

 creased by division of the chorda. But if section of the sympathetic 

 is not performed for several days, it has no effect on the paralytic 

 secretion, which at this stage seems to depend on local changes in 

 or near the gland itself, leading to a mild continuous excitation 

 of those nerve-cells on the course of the fibres of the chorda to 

 which reference has already been made. Section of the sympathetic 



