LESSON XX. 



SALIVARY GLANDS. 



1. Serous glands. With fine-pointed scissors 

 cut off a thin piece of the parotid gland of a 

 recently killed mammal, e.g. of a cat or rat ; mount 

 without adding fluid, press lightly, and examine 

 under a high power (oc. 4). If the piece is thin, 

 the alveoli will be seen, appearing as roundish masses 

 crowded with small granules. Run 2 p.c. NaCl solution 

 under the cover-slip, and tap the cover-slip firmly once 

 or twice (first sopping up excess of salt solution, if it 

 moves easily when touched). Observe the numerous 

 granules in the fluid. The outlines of the cells will 

 probably be seen in some of the alveoli. 



Salt solution *75 p.c. may be used instead of 2 p.c., 

 but in this the granules swell up somewhat, and soon 

 become indistinct. 



2. Prepare a specimen as in 1, pressing the cover-slip to 

 obtain some separated alveoli or clumps of cells. Irrigate with 

 HC1 '2 to *4 p.c. Note that the granules disappear like bubbles 



