A. THE GENERAL PHYSIOLOGY OF CILIARY MOTION. 



1. a. Normal ciliary motion, b. Ciliary motion modified 



by the influence of narcotics and stimulants. 



a. Normal ciliary motion. 



/. Appliances. Microscope, cell slide and cover glass; 

 normal saline solution (NaCl 0.6 %, Appendix 

 A, 1); physiological operating case (App. A, 3); 

 filter paper; frog or fresh water clam or mussel. 



2. Preparation. If a lamellibranch be used one need only 



snip off, with the small scissors, a bit of the margin of a 

 gill and mount it in a drop of normal saline solution 

 on a cover slip, invert the cover over the cell of the 

 cell slide and focus under low power. If a frog be 

 used it will be necessary to pith it as a preliminary 

 step. 

 j. Operations. To pith a frog. 



(1). Grasp it with the left hand, holding the legs ex- 

 tended, one on either side of the little finger in such 

 a way as to bring the dorsum of the frog toward the 

 palm of the hand. 

 (2). With the thumb and index finger fix the frog's 



nose and press it ventrally. 



(3). Place the point of a narrow bladed scalpel in the 

 median-dorsal line over the space between the occi- 

 put and atlas, i. e., over the occipito-atlantal mem- 

 brane. This point is most readily located by using 

 the eyes as a landmark. The occipito-atlantal mem- 

 brane lies at the apex of an equilateral triangle whose 

 base has its extremities in the center of the cornece. 

 Having located the point for incision, press the 

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