188 APPENDIX 



attention only to those more striking points which are very 

 definitely demonstrable. 

 Frog A. Normal: 



Attitude, breathing, reactions in water (swims and stops), 

 righting when laid on back, vision, reaction to tactile stimuli 

 (response varies with intensity of stimulus), and croaking 

 (particularly when touched behind fore legs). 

 Frog B. Hemispheres and diencephalon removed: 



Attitude, breathing, reaction in water (swims until exhausted), 

 righting when laid on back, vision, reaction to tactile stimuli 

 (response varies with intensity of stimulus), and croaking 

 (particularly when touched behind fore legs). 

 Frog C. Entire brain removed: 



Attitude, breathing, reactions in water, righting, reaction to 

 tactile stimuli, and croaking. Reflex acts: Hang up by tip 

 of jaw. Touch at various places; pinch toe, first gently, 

 then harder; acetic acid applied with bit of filter paper to 

 ventral surface, side, and back; hold the foot used in at- 

 tempted removal of acid; note purposive nature of these 

 reflex actions and crossing over to other side of body under 

 certain conditions. Call attention to diagram of cross sec- 

 tion of cord and nerves (Fig. 24 A, p. 26). 

 Frog D. Entire brain and cord destroyed: 



Make tests as for frog C. 



To show that muscle and nerve have not lost power to func- 

 tion, cut across middle of body, remove viscera, and hang 

 up hind legs. Apply chemical, thermal, mechanical, or 

 electrical stimuli to the sciatic nerve. A muscle-nerve prep- 

 aration can be used here. Refer to cross section of spinal 

 cord and emphasize the central nervous system as a con- 

 necting link between the afferent and efferent nerves of the 

 peripheral system. 



The heart may be removed from the frog and allowed to beat 

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

 as further material from which to discuss the meaning of 

 life and death. 

 Record of observations: 



The student should record his observations in the form of a 

 table filling an entire sheet of drawing paper and hand it in 

 as one of the regular laboratory exercises. The statements 

 concerning localization of function, as specified in the exer- 

 cise, should be written on a separate sheet. 



