186 APPENDIX 



D. Demonstration of Capillaries (Exercises 15 and 34, Frog) 



The animal may be prepared for demonstration without 

 anaesthesia but such specimens are likely to be troublesome. 

 If anaesthetized use ether, not chloroform, or preferably 

 • chloretone. For the latter make a solution of 4 parts 

 Ringer's solution to 1 part 0.5% chloretone in water. Im- 

 merse the frog in this solution about 30 minutes or until 

 quiet; do not leave longer than necessary. Then wrap the 

 animal in wet cheese cloth, with care not to bind too closely, 

 leaving one hind foot exposed. Fasten animal to a frog 

 board and spread web of foot. Soft twine can be tied to 

 the ends of toes and fastened to pins to avoid pinning 

 through any part of the foot. Place the web so that ob- 

 servation can be made with the low-power objective. Keep 

 the surface of the foot moist throughout the demonstration; 

 a cover glass with a generous drop of water beneath it can 

 be used. 



E. Functions of the Sensory-neuro-muscular System (Exercise 21, 



Frog) 



Equipment: 



Frogs, A, B, C, and D. See directions for operation. 



The same frog may be used for B, C, and D. 



Jar of water for frog to swim in. 



Bell-jar to place over frog A. 



Bunsen burner. 



Ring stand. 



String and bent pin or fish-hook. 



Scalpel, scissors, forceps, dissecting needles. 



Pithing needle. 



Dissecting pan. 



Watch glass. 



Strong acetic acid. 



Filter paper. 



0.7% salt (NaCl) solution, or Ringer's solution. 

 Directions for operation (see Fig. 78) : 



Frog A. Normal. No operation. 



Frog B. Cerebral hemispheres and diencephalon removed. 

 Cut through the roof of the skull at a, sever the brain, and 

 pith forward. Or for a more precise operation, etherize frog, 

 lay back skin, remove roof of skull, and carefully dissect out 



