26 



(d) Fat Cells. 



The mesentery of a cat was spread on a large glass slide, 

 hardened for 48 hours in 95% alcohol, stained in hsematoxylin, 

 washed in water, dehydrated, and cleared in oil of bergamot. A 

 small portion including an arteriole is cut off with scissors, trans- 

 ferred to the slide, and mounted in balsam. 



Study first under low power, and observe the large, 

 clear, round or oval, cells, arranged in rows or small groups 

 on either side of the small vessels. Under high power a 

 nucleus is now and then made out. A network of capil- 

 laries embracing the fat cells is often observed. Sketch as 

 seen under low power. 



(e) Section of Adipose Tissue. 



A small portion of the skin was hardened in absolute alcohol, 

 stained in borax carmine, embedded in paraffin, and sectioned. 

 Fix to the slide and mount. 



Study under low power. Notice the groups of fat cells, 

 lobules of fat, separated by bundles of fibrous connective 

 tissue. Sketch as seen under low power. 



(f) Endothelial Cells. 



A \% solution of silver nitrate was injected into the peritoneal 

 cavity of a frog. After 15 minutes the intestines with the attached 

 mesentery were removed, pinned out on a small piece of cork, placed 

 into 95% alcohol, and exposed to the sunlight until it assumed a 

 brown color. After dehydration the tissue was cleared in oil of 

 bergamot. Mount in balsam. 



Study under high power, and observe that the silver is 

 deposited in the intercellular cement substance, a delicate 

 black line surrounding and outlining each cell. Now and 

 then the protoplasm and nuclei are stained a light brown. 

 Sketch as seen under high power. 



