34 



EXPERIMENTAL GENERAL PHYSIOLOGY 



varying the height of the receptacle into which the siphon dips or 

 through adjustment of the screw clamp or of the spring clamp at d, 

 the pressure and the rate of flow of gas are under perfect control. 

 Prepare a specimen of cilia for observation with a low-power micro- 

 scope. (Great care must be taken to remove all of the mucus, other- 

 wise the CO 2 may have little effect on the cilia.) Bring a good 

 specimen into the field, focus the microscope, and observe the rate 

 and character of ciliary movement. Remove screw clamp at S. 



FIG. 11 



Apparatus for forcing a stream of gas or vapor through a microscopic slide chamber. 

 (For description see text.) 



2. Observations, (a) The effect of C0 2 upon ciliary activity. 



(1) While observing closely the normal action of the cilia, press 

 the spring clamp gently for a few moments. If after half a minute 

 or more no noticeable change takes place in the rate of movement 

 of the cilia, repeat the dose of gas. What is the effect of CO 2 gas 

 upon the activity of cilia? 



(2) After the effect of gas has become apparent, clamp the tube 

 at d; disjoin at glass tube beyond and gently draw air through the 

 cell, thus ventilating it and restoring practically the normal condition. 

 Do the cilia resume the normal movement? 



(3) How many times may the cilia be narcotized to the point of 

 complete cessation of activity and then by ventilation be revived 

 again? 



(6) The effect of chloroform gas upon ciliary activity. 



(4) Clamp tube at S; remove flask from apparatus; fill flask with 

 water to expel CO 2 ; empty. (Suspend in the flask a wad of cotton 

 saturated with chloroform or ether.) Make a new preparation of 

 cilia and observe normal movement. 



