70 PRACTICAL HISTOLOGY. 



( 63, ). A slight increase of temperature accelerates the 

 ciliary motion, probably by hastening the chemical changes 

 on which it depends. A too high temperature arrests the 

 movement, doubtless by destroying the delicate molecular 

 machinery of the contractile substance. 



89. Effect of Chloroform (H.) To study the effect of 

 chloroform vapour on ciliary motion, first shown by Mr. Lis- 

 ter, take a slide with a glass cell (Fig. 6 2, b) or make a cell with 

 a ring of putty, and place it on a slide. Place a small piece 

 of the mussel's gill in a drop of sea water on a cover-glass. 

 Put a small drop of chloroform in the cell ; invert the cover- 

 glass over it, so that the preparation will hang into the cham- 

 ber. Find the focus quickly, and observe that the ciliary 

 movement gradually comes to a standstill. The chloroform 

 molecules evidently penetrate the contractile substance of 

 the cilia, and inhibit or restrain those chemical or other 

 changes in its molecular machinery that are essential for 

 the contractile movement. If when the movement is 

 nearly at or has just come to a standstill the cover-glass 

 be removed, the cell washed out, and the preparation 

 exposed for some time to the air, the chloroform molecules 

 escape, and the movement is resumed. This experiment 

 may be more easily performed with the aid of a gas- 

 chamber (Fig. 49). 



90. Effect of Carbonic Acid and Oxygen With the aid 

 of a gas-chamber (Fig. 49), and cilia from the mussel's gill or frog's 

 pharynx, arranged as in the last experiment, the effects of various gases 

 may be studied. 



A stream of carbonic acid (supplied by the usual apparatus, Fig. 46) 

 at first accelerates, but soon retards, and finally arrests the movement. 

 On the substitution of a stream of oxygen or air the movement is after 

 a time resumed. (Kiihne.} 



91. Effect of Alkalies The addition of a very dilute solution 

 of caustic potash accelerates the movements of cilia when these are 

 becoming sluggish previous to their death ; it may even recall the 

 movement after it has ceased for some time. (Virchow.} 



For other experiments on ciliary motion see Kiihne, Schultze's 

 Archiv, ii. 372; Engelmann, Journ. of Anat. and Physiol., iii. 420. 



92. Structure of Ciliated Epithelium (H.) Ciliary 



