CYTOLOGY 33 



lift the stomach up vertically above the sternum, and make moderate 

 traction. The delicate and elastic submucosa about the end of the 

 oesophagus will yield to the traction and the whole oesophagus will 

 be readily separated from the surrounding tissues and wholly removed 

 from the frog. 



' (5) Open the stomach and oesophagus by means of a longitudinal 

 incision through their walls; stretch them on a cork board, fixing 

 with pins, and gently wash off mucus with normal saline solution 

 and cameFs-hair brush. Remove the excess of liquid with the help 

 of filter paper. ^ ^<//tX^*oE^\cA. 



3. Observations. '(1) Place a small piece of cork upon the anterior 

 end of the oesophagus. Does the cork move? If so, in what direction 

 and at what rate? 



(2) Will the cork pass over the boundary line between oesophagus 

 and stomach, and will it move over the surface of the stomach? 



(3) To determine the ca,use for the movement of the cork, cut a 

 minute portion of mucous membrane from the crest of one of the 

 folds, place it in a hanging drop of saline solution mounted over a 

 cell slide, and examine with a microscope. If the preparation has 

 been properly made the margin of the tissue should, at certain points, 

 show the cause for the phenomena above observed. Study the 

 character of the ciliary movements. Describe. 



(4) Study ciliary movement with higher power. It is probable 

 that' the first preparation is not suited to observation with a high 

 power. If the cilia cannot be readily brought into focus, prepare 

 a second one as follows: From the ciliated surface clam-gill or 

 frog-oesophagus scrape a few epithelial cells with the point of a 

 scalpel, place the minute bit of tissue upon a cover-glass, add a small 

 drop of saline solution, gently tease the tissues with needles, and invert 

 the cover upon a slide, allowing one edge to rest upon a hair, to 

 avoid undue pressure upon the tissue. 



Focus under high power (300 to 600 diam.). If the preparation 

 is successful, groups of ciliated cells may be seen and the character 

 of the ciliary movement studied. 



V. CILIARY MOTION MODIFIED BY THE INFLUENCE OF C0 2 



AND ANESTHETICS. 



ViV * \ j 



1. Appliances. In addition to the appliances enumerated in the 

 foregoing lesson one needs a ventilating apparatus with ventilated 

 cell slide. Chloroform, ether, absolute alcohol. 



Fill the glass flask full of water and displace it with CO 2 gas. 

 Fill the siphon and adjust apparatus as shown in Fig. 11. During 

 any readjustments of the apparatus the siphon may be kept filled 

 and ready for action by putting on a screw clamp at S. Through 



3 



