62 LABORATORY MANUAL OF GENERAL PHYSIOLOGY 



locomotor movements? Compare with an intact animaL Stimulate with a 

 needle. Note degree of flexion of appendages. 



Fig. 5. — Diagram of the nerve cord of the crayfish. Note position of circumo esophageal con- 

 nectives in relation to green gland (stippled) and alimentary tract (dotted lines). 



9. Functions of Ventral Nerve Cord. — Cut the commissure between 

 the suboesophageal and the first thoracic ganglia. Compare the behav- 

 ior of animal in all points with that prior to the operation. Cut across 

 the ventral nerve cord between the thorax and 

 abdomen. Any voluntary control of append- 

 ages? Can individual appendages give reflex 

 movements? Consult Roger's "Comparative 

 SI^TI^H%^«Es/cf''% Physiology," p. 525. 



CEREBRUM OF FROG 



OPTIC LOBES 



10. Effects of Decerebration on the Frog. — 



(The following operation should be performed 

 very carefully with well sharpened sterilized 

 instruments.) Anesthetize slightly with ether a 

 male frog (just ceases to show equilibrium 

 reflexes). If effect of ether wears ofif replace in 

 ether jar. 



The cerebral hemispheres extend back to a 

 line connecting front margins of tympanic mem- 

 branes. Cut skin along this line over top of 

 skull. From this cross-cut make median inci- 

 Fig. 6.— Dorsal aspect of frog's ^j^q^ forward nearly to nostrils. At intervals 

 wash with antiseptic Ringer's solution (HgCU 

 1:2,000). Lay back the flaps. With scissor points separated to either side 

 of top of skull, immediately in front of transverse incision, cautiously bring 

 points together by cutting barely through bone. Insert the sharp blade 



