518 APPENDIX 



turally normal. In an hour or less the nervous shock of the operation 

 passes off and the functions of the hemispheres may be demonstrated by 

 noting what the hemisphereless frog does not and cannot do that the 

 normal animal does 



(A) Shock. Note the characteristics of the nervous shock of the opera- 

 tion : the entire lack of muscular tone, etc. (B) Muscular Action and 

 Posture not Disturbed. Wait until the shock has passed off (doing 

 some other experiment meanwhile). The heart-beat, respiratory move- 

 ments, intestinal peristalsis, etc., continue and the eyes are open (and 

 probably seeing, although the frog does not recognize objects). The 

 skeletal muscles have recovered their tone and the posture of the animal 

 is nearly or quite normal (the cerebellum and cord remain). (C) Spon- 

 taneity Lost. Note that, unstimulated, the frog does not move. Were 

 it quite unstimulated, the animal would die of thirst, hunger, or drying 

 without changing its position; intelligence as conceptualization is entirely 

 lacking. (See Chapter XII., page 416.) (D) Equilibrium Maintained* 

 The frog will not remain in a supine position. If placed on the back of a 

 hand that is then slowly turned over, the animal keeps its equilibrium 

 by the appropriate complex movements, and does not fall off. The 

 optic thalami remain, but spontaneous movement is never made: there 

 is no deliberate will. (E) Vision Unimpaired. Place some small opaque 

 object (such as a dissecting-case on end) in front of the frog on the table, 

 and pinch a hind foot. The animal jumps, but the object is avoided. 

 (F) Biological Reflexes Persist. In water deep enough, swimming is per- 

 fectly carried out, and the frog may even climb on the rim of the tank and 

 sit there. The sexual embrace is unimpaired. Food put in the mouth 

 is swallowed. (G) Intelligence Gone. However much irritated, the frog 

 does not hide as a normal frog would do, but jumps only once or twice 

 and then sits quietly again. Every sort of recognition is gone with the 

 fusion-processes of the cortex cerebri. The animal sees the danger, food,, 

 water, etc., but not recognizing what they are, cannot make the appro- 

 priate actions. 



IX. GALVANOTAXIS AND CHEMOTAXIS. 



Expt. 89. Galvanotaxis. (Apparatus: Frog-tadpoles, wax, glass 

 dissecting-plate, two dry-cells, key, commutator with cross-wires, stand- 

 rod, femur-clamp, 0.1 per cent, sodium-chloride solution.) Make a 

 wax trough about 6 cm. long, 2 cm. wide, and 1 cm. deep on the glass 

 dissecting-plate and have it carefully water-tight. Fill with the solution 

 of sodium chloride. Place within it seven or more frog-tadpoles not over 

 2 cm. long. Clamp the wires from the commutator (with cross-wires) 

 in the femur clamp in such a way that an end of one may be in the saline 

 at each end of the trough. Determine which pole is now the anode and 

 close the key so that three volts may pass through the liquid. A majority 

 of the tadpoles, after being shaken up, collect about the cathode. Reverse 



