BIOLOGICAL INTRODUCTION. 



cork board at an angle of about thirty-five degrees. Flat weights 

 will be necessary on account of the incline. Measure the height of 

 the upper edge of the preparation from the lower edge. Observe 

 the time taken for the passage of a given weight through this dis- 



FIG. 5. To Show Ciliary Motion. (According to Kronecker.) E, Portion of frog's 

 oesophagus ; W, cork with weight ; P, pointer ; S, scale. 



tance. Estimate the work by the cilia, according to the following 

 formula: W, work done; G, weight in milligrams; H, height in 

 millimetres. W, then, would equal G multiplied by H. What is 

 the work done per second ? Per minuute ? 



4. Effect of C0 2 on Ciliary Motion. (a) Fill a small bell jar 

 with water and invert over water. Introduce a tube from a CO 2 

 generator and fill the jar with the gas. Pin an oesophagus prepara- 

 tion to a cork board and place on a glass plate greased with vase- 

 line. Place a cork with weight upon the preparation. Quickly 

 adjust the gas containing jar over the ciliary preparation. Ob- 

 serve the rate of ciliary motion, as before. What is the effect of the 

 gas? 



