CHAPTER I 



AMCEBOID AND CILIARY MOVEMENT 



The fresh-water amoeba. Find an amoeba in a drop of pond water with 

 the microscope, and study its movements. 



Amoeboid movements of frog's leucocytes. Observe in a preparation of frog's 

 blood the amoeboid movements of the leucocytes. 



Ciliary movement. (1) Gently scrape some epithelium from the roof of a 

 frog's mouth, and shake the scrapings in a drop of normal salt solution or of 

 Ringer's solution. 1 Observe with the microscope the ciliated cells and the 

 movements of their cilia. 



(2) Take a small fragment of the gills of a sea-mussel and examine it under 

 the microscope in a drop of sea water. The cilia are much larger than those 

 of the frog, and their movements more easily watched, especially when they 

 become slow. 



Experiments illustrative of amoeboid movement. The following experiments 

 show that movements like those of the amoeba can be produced by purely 

 physical means (changes in surface tension). 



1. Take on a glass rod a drop of ordinary olive oil which has been coloured 

 with Scharlach R., and place it gently on the surface of a 1 per cent, solution of 

 sodium bicarbonate. Sketch the changes of shape which it undergoes. 



2. A globule of mercury is placed in a watch-glass of dilute nitric acid (1 

 per cent.). Introduce into the fluid near, but not touching, the drop a small 

 crystal of potassium bichromate. Observe the movements of the mercury. 



Experiments on ciliary movement. 1. In a model consisting of a thick 

 rubber ball from which a flat, curved rubber tube projects, notice that the tube 

 straightens out or curves over to one side according to the tension of the contents 

 of the ball. This movement, which resembles that of a cilium, is thus produced 

 by variations in tension within the part representing the cell. 



2. In a frog which has just been killed, cut through the lower jaw and carry the 

 incision down the oesophagus to the stomach. Cut this organ across, seize the 

 cardiac end with forceps, and dissect out the oesophagus together with the 

 pharynx and a part of the mucous membrane of the mouth. Pin out the oeso- 

 phagus and pharynx and adjacent parts of the buccal membrane on a flat cork 

 with the inner surface uppermost. Rinse with Ringer's solution. Sprinkle a 

 few grains of charcoal over the buccal end of the preparation, and notice that 

 the charcoal is carried down as far as the stomach by the action of the cilia. 

 In the same way, pieces of cork or wax, or even small flat pieces of heavy materials 

 such as lead, may be passed over the surface. 



1 Normal salt solution is made by dissolving six grams Nad in a litre of 

 water. Ringer's solution is an improved salt solution made by saturating one 

 litre of the above with calcium phosphate and adding ten milligrams of 

 potassium chloride. '' Ringer " should always be used in preference to ordinary 

 salt solution. For mammalian tissues it is made similarly but with 79 grams 

 NaCl to each litre of water. 



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