XV.] SALIVARY GLANDS AND PANCREAS. SALIVA. 159 



by the reagents used) and are placed nearly 

 in the centre of the cells (they are usually a 

 little nearer the outer side). 



2. Tease out in normal salt solution a small piece 

 of the parotid of a rabbit (preferably one which 

 has been killed eight to ten hours after a full 

 meal). 

 Observe the numerous granules in the cells. 



C. Pancreas. 



1. Cut sections of 'resting" pancreas (dog, rabbit or 

 frog) which has been preserved in osmic acid; 

 mount the sections in dilute glycerine. Observe 



a. Under a low power; the gland consists of 

 lobes, lobules and alveoli like the serous and 

 mucous glands. 



b. Under a high power; the cells contain a 

 great number of granules which stretch 

 nearly or quite to the outer border; the 

 nuclei are more or less completely hidden by 

 the granules. 



2. Cut sections of active' pancreas and compare 

 with the above. 



1 By a 'resting ' gland is meant one which has not been secreting, or 

 has been secreting slightly only, for several hours ; by an ' active ' gland 

 is meant one which for an hour or more has been secreting rapidly. 

 In both cases the animal Is understood to be in a good state of nutri- 

 tion ; the pancreas of an animal which has long fastedisnota' resting ' 

 pancreas. With the dog or rabbit the gland should be taken five to 



