358 Journal of Comparative Neurology and Psychology. 



moreover, abnormal positions of the limbs, for instance, adduction of both fore- 

 legs until they almost touched each other. 



VI. The sixth operation consisted in burning both lobi and thalami optici. 

 It caused total blindness on both sides ; reduction in voluntary movements and 

 touch-sensibility, as noticed after bilateral removal of the thalami optici and the 

 other defects of unilateral excision of the thalamus and lobus opticus, but in a 

 much more marked degree. The abnormal retention of urine was one of the 

 first phenomena to disappear ; three weeks after the operation it was no longer 

 noticeable. The forced movements also improved, and were not noticeable after 

 two weeks unless the animal was greatly excited. The sight was permanently 

 abolished on both sides. 



VII. The seventh operation — consisting in unilateral burning of the lobus 

 opticus — caused slight defect in sight on the crossed side, straight forced move- 

 ments, and abnormal retention of urine. The last two phenomna were as indi- 

 cated in operation V. Sight was normal on both sides after two weeks. 



VIII. After the next operation in which both lobi optici were removed, the 

 trifling defect in sight was bilateral, the straight forced movements were stronger, 

 and the retention of urine more pronounced than after unilateral excision of the 

 lobus opticus. The forced movements and the abnormal retention of urine 

 improved as indicated in operation VI, and the slight bilateral defect in sight 

 improved within ten days so as not to be detected. 



IX. The ninth operation, which consisted in removing the anterior half of 

 the two lobi optici, showed, during the first two weeks, the abnormal retention 

 of urine and slight bilateral loss in sight, as noted under bilateral removal of the 

 lobi optici. Later, until two and a half months after the operation, sight was 

 normal on both sides, and urinary retention gradually disappeared during three 

 weeks after the operation. 



X. In the tenth operation the posterior half of both lobi optici was re- 

 moved, and the result was that the forced movements became apparent as noted 

 in operation VIII. Later these were present only when the frog was extremely 

 excited. 



XL By removing both optic thalami and the anterior half of the lobi optici 

 all the phenomena as noted under bilateral removal of the thalami and lobi op- 

 tici, with the exception of the forced movements, were noticed. 



XII. By burning the dorsal half of both thalami and lobi optici sight was 

 only slightly injured for two weeks, whereas the abnormal retention of urine, the 

 forced movements, the depression of voluntary movements and touch-sensibility 

 were injured according to the amount of nerve tissue removed. 



XIII. After bilateral removal of the cerebellum, the jumps became 

 very unsteady and were weakened in force but not much reduced in rate. Most 

 of the time the frog lay stretched in contact with the floor of the vessel and cov- 

 ered with moss. The unsteady and weakened condition of the limbs persisted in 

 a marked degree two and a half months after the operation (especially when the 

 frog was greatly excited). The frog's hibernating tendency persisted two and a 

 half months after the operation and it did not succeed in catching flies put into 

 its cage. 



XIV. Unilateral excision of the cerebellum caused a number of phenomena 

 which also appeared more pronounced after unilateral excision of the medulla an- 



