702 THE CEREBRAL CORTEX. 



more truly of a voluntary character than the corresponding limbs of 

 pigeons. 



The results in mammals of complete removal of the cerebral hemi- 

 spheres have been investigated in the guinea-pig and rabbit by many 

 physiologists. The rabbit, after removal of the hemispheres, in a few 

 minutes sits up and begins to move about in an apparently normal 

 manner. 1 Its reflex excitability is increased. If the foot is pressed, it 

 will kick and struggle violently, and may rush forward, as when the 

 corpora striata are destroyed. 2 But if the thalaini be included in the 

 lesion, the movements are much more limited, and, according to Chris- 

 tiani, 3 progression is no longer possible. Eecently the removal of the 

 hemispheres has been effected in a very complete manner by Goltz in 

 the dog. The following description is founded on Goltz's observations 4 

 upon an animal in which both cerebral hemispheres were completely 

 removed in successive operations, the corpora striata and the optic 

 thalami being also partly involved in the lesion. 5 One optic nerve was 

 also severed, and of course the olfactory lobes were included. The 

 hemispheres were removed in three successive operations. The dog was 

 kept alive for eighteen months after the final operation. After complete 

 recovery from the last operation, the animal was able to walk in a 

 perfectly normal fashion ; towards the end of the period, however, its 

 movements became gradually weaker, the hind-legs especially becoming 

 emaciated and suffering loss of power. For the greater part of the day 

 it walked restlessly up and down in its cage, but at night would go to 

 sleep, rolled round in the manner usual with dogs. It then required a 

 loud sound such as that of a horn, or rough shaking to awaken it. 

 When awake it reacted to loud sounds by shaking its ears, to a glare of 

 light by shutting its eyes, and by turning its head away. It reacted 

 promptly and consequentially to tactile impressions. When its skin 

 was pinched, it gave vent to its discomfort by snarling or barking just as 

 a normal dog might do, and attempted to get away from the hand 

 which was the source of discomfort, or failing to do this would turn 

 round and bite at it, but in a clumsy manner and often without coming 

 near it. If its feet were placed in cold water, they were quickly with- 

 drawn. If one of its limbs was placed in an abnormal or uncomfortable 

 attitude, it would never be allowed to remain so, although a dog with a 

 lesion of the frontal cortex only does not replace a limb which has been 

 put into such a position. If its fore-feet were placed upon the flap of a 

 table, which was then gradually lowered, the legs would only be allowed 

 to follow the flap for a short distance; the equilibrium was speedily 

 recovered ; a dog with the frontal centres only removed would fall 

 under these circumstances. When one foot was accidentally hurt, the 

 animal limped about for a time on three legs, in the manner usual with 

 dogs. 



Like the frog, fish, and bird in a like condition, the animal for 

 months took no food spontaneously but had to be artificially fed by 

 placing food at the back of its mouth, and even then often choked in the 



1 Vulpian, "Lecons," etc., 1866. 



- See Nothnagel, Virchoufs Archiv, Bd. Ivii. S. 184, 206. 



s Verhandl. d. physio/. Gesellsch. zn Berlin, Arch. f. Physiol., Leipzig, 1884, S. 465. 



4 "Der Hund ohne Grosshirn," Arch. f. d. ges. PhysioL, Bonn, 1892, Bd. li. S. 570. 

 Other experiments by Goltz of a like nature are described in previous volumes of the same 

 journal, but the removal was in no other case so complete. 



5 Edinger, Neurol. CentralbL, Leipzig, 1893, Bd. xii. S. 327. 



