158 ELEMENTARY PHYSIOLOGY. [XV. 



a. The mucous and demilune cells are much 

 more alike. 



b. The mucous cells are smaller, and a much 

 larger part of their cell-substance is stained, 

 the unstained part being as before next 

 the lumen. Their nuclei are spherical in- 

 stead of disc-shaped, lie more towards the 

 centre of the cells, and have conspicuous 

 nucleoli. 



Some alveoli and patches of alveoli shew the 

 changes mentioned above much more distinctly 

 than others, in some the only changes observable 

 are that the demilunes are more conspicuous, 

 and the nuclei of the mucous cells spherical. 



B. SEROUS SALIVARY GLANDS. 



1. Prepare specimens of a mammalian parotid gland 

 or of a submaxillary gland of a rabbit. The 

 tissue may have been preserved in alcohol (cp. 

 A. 1) or in *2 p. c. chromic acid. Compare 

 with the section of the mucous gland (A). 

 Note that in the alveoli 



a. The cells are more or less polyhedral, having 

 less rounded outlines than the cells of the 

 mucous gland. One kind of cell only is 

 present. 



b. The cells stain fairly equally throughout 

 and appear to be densely granular. 



c. The nuclei are spherical (unless shrunken 



