502 MUSCLE-NERVE PHYSIOLOGY 



30 C. automatic contractions will sometimes occur in it. Smooth muscle 

 responds like voluntary muscle to variations in temperature, to fatigue, strength 

 of stimulus, etc., etc. 



1 6. Ciliary Contractions. Ciliated Epithelium. Make a prepara- 

 tion of ciliated epithelium by cutting out the esophagus of a terrapin or frog, 

 slitting it open longitudinally, and smoothing it out on a cork block. The cilia 

 of this membrane will drive in the direction down the esophagus. Test the 

 rate at which different loads are moved and measure the distance on the prep- 

 aration as follows : Cut pieces of clean white paper about 4 and 6 mm. square. 

 Select a favorable area on the ciliated surface as long as possible, place the 4 

 mm. square paper at the beginning of the area, and measure the time which it 

 takes to travel the distance. Measure the speed in terms of seconds per cen- 

 timeter. Now replace the paper at the point of beginning and load it with 

 small weighed cubes of paraffin. The rate at which the load is carried will 

 slightly increase at first as the load is increased, but later will sharply decrease. 

 Elevate one end of the ciliated membrane and repeat the experiment with 

 different loads so that the cilia will now carry the load uphill. Calculate the 

 work done in terms of gramcentimeters of work per square centimeter of 

 ciliated surface acting on the load. 



