160 PRACTICAL HISTOLOGY [XX 



stains equally throughout, resembles that of the cells 

 of the serous glands. 



The ducts are in general features like those of the 

 serous glands (cp. 3). 



7. Active mucous gland. Section of dog's sub- 

 maxillary gland after prolonged secretion 1 . The section 

 should be stained in the same way as that of 6. 

 Observe, comparing it with the resting gland of 6 ; 

 the mucous cells are smaller, owing to a diminution 

 in the mucous part of the cell, and have less rounded 

 outlines ; the mucin which remains borders the lumen. 

 The protoplasmic cell substance is more abundant. 

 The nuclei are spherical, have conspicuous nucleoli, and 

 are farther from the basement membrane. 



The alveoli are not all changed to the same extent ; 

 in some the mucin has almost entirely disappeared, and 

 the demilune cells are more polyhedral, so that the two 

 kinds of cells are not very easy to distinguish; in others 

 the chief change observable is that the nuclei of the 

 mucous cells are spherical. Dividing nuclei are as 

 rare as in the resting gland. 



8. Tease in 5 p.c. neutral ammonium chromate a piece of a 

 dog's sub-maxillary gland which has been kept for 3 to 6 days in 

 the fluid (2 p.c. chloral hydrate may be used for the ammonium 

 chromate). Observe the isolated mucous and demilune cells. 

 The general appearance of a mucous cell is like that produced 

 by dilute HC1 in 5, but the basal end of the cell is seen to be 

 prolonged into a process. 



1 In a dog under morphia and chloroform, the chorda tympani 

 (or this with the sympathetic) is stimulated at short intervals for 

 three to six hours. 



