370 Journal of Comparative Neurology and Psychology. 



(2) Other symptoms as noted under operation V, but in a more marked 

 degree, 

 (b) From three weeks to two and a half months, (i) remains unimproved, 

 (2) normal, (3) other symptoms as noted under operation V (b). 



VII. Unilateral removal of the lobus opticus. 



(a) From one half hour to two weeks, 



(i) Trifling defect in sight on crossed side.i 



(2) Forced straight-ahead movements and abnormal urine retention as 

 noted after operation V (a). 



(b) From two weeks to two and a half months, 



(i) Sight is normal. 



(2) The other two symptoms as indicated in operation V (b). 



VIII. Removal of both lobi optici. 



(a) From one half hour to two weeks, 



(i) Trifling bilateral defect in sight. 



(2) The other symptoms as noted under operation VII (a), but stronger. 



(b) From two weeks to two and a half months, 



(1) Sight is normal on both sides. 



(2) The other symptoms as noted under operation VII (b). 



IX. Removal of the anterior half of the lobi optici. 



(a) From one half hour to two weeks, 



(1) The same symptoms as after operation VIII (a), excepting that the 



forced movements were absent. 



(b) Later, to two and a half months, the animal showed nothing abnormal. 



X. Removal of the posterior half of the lobi optici, 



(a) From one half hour to two weeks, forced straight-ahead movements. 



(b) Later, to two and a half months, the forced movements are present only 



when the animal is much excited. 

 XL Removal of both thalami optici and the anterior half of the lobi optici. 



AllJ symptoms are noted under operation VI excepting that the forced 

 movements were absent. 



XII. Removal of the dorsal half of both thalami and lobi optici. 



All symptoms as noted under operation VI but in a lesser degree, whereas 

 sight was only slightly and temporarily (two weeks) aftected. 



XIII. Bilateral removal of the cerebellum. 



(a) From a half hour to three weeks, 



(i) Flat position of the frog. 



(2) Jumps infrequent, weak, and unsteady. 



(b) Later, to two and a half months. 



Muscular weakness and unsteadiness is marked only when the frog is ex- 

 cited ; the animal is unable to catch flies, although it sees them. 



XIV. Unilateral removal of the cerebellum, 

 (a) From a half hour to one week, 



(i) Limbs of crossed side, especially the posterior one was abnormally 

 far extended and abducted. 



(2) Locomotion is always toward the homonymous side. 



(3) Head was lower and almost touched the ground on the homony- 



mous side. 



