APPENDIX 189 



m. MISCELLANEOUS SUPPLEMENTARY DIRECTIONS 



A. Maceration of Columnar Epithelium (Exercise 29, Frog) 



Cut the anterior two-thirds of the small intestine of a frog 

 recently killed by pithing into pieces 2-3 mm. long. Place 

 in 30% alcohol for 8-12 hours before the meeting of the 

 class. When the student obtains the material he should take 

 a drop of the alcohol. 



Another method which can be used to obtain a permanent 

 stock of columnar epithelium is to cut the small intestine 

 of Necturus lengthwise, wash it quickly if necessary, and 

 cut into pieces about 1 cm. long. Place in 30% alcohol for 

 8-12 hours. Check to see if maceration is satisfactory and 

 transfer to 80% alcohol. This should be changed, by de- 

 canting, after about 24 hours. The columnar cells can be 

 shaken off and given out for study in drops of the fluid. 

 Students need to be warned about the rapid evaporation. 



B. The Effect of Ciliary Action (Exercise 30, Frog) 



To demonstrate ciliary currents in the roof of the frog's mouth 

 kill the animal by pithing and remove the lower jaw and 

 floor of the mouth. Open the ccelom and remove the vis- 

 cera, leaving as much of the esophagus as possible. With 

 the specimen pinned out in a dissecting pan, sprinkle fine 

 particles of cork or lead filings on the anterior end of the 

 ciliated roof of the mouth. They will be carried posteriorly 

 to the esophagus and emerge through its cut end in the 

 ccelom. The epithelium must be kept moist with salt 

 solution. 



C. Maceration of Non-striated Muscle (Exercise 35, Frog) 



Pieces of intestine can be cut about 1 cm. in length and placed 

 in 35% potassium hydroxide (KOH). The length of time 

 must be determined for the thickness of the wall; the best 

 time for the rat is 15 minutes. Pour off the potassium 

 hydroxide and cover the pieces with glacial acetic acid for 

 an hour or more. Wash thoroughly in water and replace 

 with 5% formalin. Shake at once to separate muscle cells, 

 which can then be kept and given out for study by the drop. 

 It is possible to remove most of the mucosa by scraping an 

 opened intestine before the maceration. 



