If. To determine the amount of work done by cilia. 



/. Appliances. Physiological operating case ; frog board ; 

 cork board 10 cm. long by 5 wide; a centimeter rule; 

 a block of wood 4 or 5 cm. in height ; a bit of sheet 

 lead 1 mm. thick; scales correct to a milligram should 

 be accessible to the student. 



2. Preparation. Pith a frog and destroy cord. Dissect 



out oesophagus and stomach as directed in lesson I. 

 Fix to cork board so that the long axis of the cesoph 

 agus shall be parallel with the long axis of the board. 

 Cut a piece of sheet lead just 5 mm. square and 

 another 3 mm. square. Weigh each of them. 



3. Operation. Wash off ciliated surface, remove the sur- 



plus moisture with filter paper, and place the lead 

 gently upon the anterior end of the oesophagus. 



The incline of the ciliated surface may be changed 

 by resting it, at different angles, against the block of 

 wood as shown in Fig. 2. 



4. Observations. 



(1) If the preparation is successful the piece of metal 

 will be slowly carried up the incline. Should it fail 

 a thinner piece of lead or a new preparation may 

 succeed. With a given incline, is the small piece of 

 lead carried more rapidly than the large piece? 



(2) If W = work done, g = weight in milligrams and 

 li = height in millimeters, then W = g X h 

 would give the work in milligram-millimeters. 



(3) Determine the distance through which the weight 

 is carried in a unit of time [one minute is a con- 



23 



