FUNCTIONS OF THE CEREBRUM. 699 



There is now no room for discussion with regard to the persistence of general sensi- 

 bility after removal of the hemispheres. The experiment upon a pigeon leaves no doubt 

 upon this point, but the susceptibility to pain has been much more strikingly illustrated 

 in other animals. Vulpian, in describing the condition of animals operated upon in this 

 way, illustrates the persistence of sensibility in rats and rabbits, by the violent cries 

 which follow painful impressions. 



In concluding our consideration of the observations upon inferior animals, it only 

 remains for us to discuss briefly certain late experiments, which have attracted a great 

 deal of attention from the fact that they seem to show that spontaneous volition exists 

 after complete extirpation of the cerebrum. These experiments have been most ably 

 and satisfactorily analyzed by Vulpian. Goltz argues, from experiments upon frogs and 

 the movements executed after extirpation of the brain, that these animals make intelli- 

 gent muscular efforts when deprived of the hemispheres ; and the phenomena observed 

 after this mutilation are indeed very curious. As was shown by Vulpian, in his own 

 experiments, frogs and fishes thrown into water will swim about and the frogs will even 

 succeed in getting out of the water, but then, they immediately relapse into a torpid con- 

 dition. We do not conceive that these facts are in opposition to the statement just 

 made with regard to the absence of spontaneous volition in birds and the mammalia, 

 particularly in view of the slight importance of the functions of the cerebrum as com- 

 pared with the spinal cord in the lower orders of vertebrate animals. The views lately 

 advanced by Yoit are based upon an isolated experiment upon a pigeon that was kept 

 alive for five months after the cerebral lobes had been, as stated by Voit, completely 

 removed. At first the pigeon presented the phenomena usually observed after this opera- 

 tion ; but it gradually recovered, until finally it seemed entirely normal, with the single 

 exception that it never would eat, all food being introduced forcibly. Five months after 

 the operation, the pigeon was killed and the encephalic cavity was found filled with a 

 white substance containing dark -bordered nerve-fibres and nerve-cells. Voit never before 

 observed any thing like regeneration of the nervous substance or so complete a restora- 

 tion of the cerebral functions ; and he regarded this as an instance of anatomical and 

 physiological regeneration of the hemispheres. The objections to accepting this observa- 

 tion with the physiological conclusions presented by Voit are, that it is not only possible 

 but probable, that the hemispheres were not entirely removed and that the posterior 

 portion of the encephalon had advanced to occupy in part the space originally filled by 

 the extirpated mass. While we do not assume that anatomical and functional regenera- 

 tion of the cerebrum in a pigeon is impossible, it must be admitted that such an extraor- 

 dinary statement as that made by Voit cannot be accepted without reserve, merely 

 upon the basis of a single observation. 



Pathological Facts bearing upon the Functions of the Cerebrum. A careful study of 

 the phenomena which attend certain pathological conditions of the brain in the human 

 subject, such as laceration or pressure from effusion of blood, softening of the nervous 

 substance, etc., taken in connection with the results of experiments upon living animals, 

 throws considerable light upon the functions of certain distinct portions of the encephalon. 

 Cerebral haemorrhage very commonly involves the corpus striatum, either directly or 

 indirectly, and then we have paralysis of motion limited to the side of the body opposite 

 to the lesion. When the optic thalamus is affected, there is impairment of sensibility 

 upon the opposite half of the body. These facts illustrate the course of the motor and 

 sensory conductors from and to the cerebrum. It is not very common to observe lesions 

 confined to the gray or white substance of the hemispheres, but, when this occurs and 

 when there is no pressure upon the corpora striata or optic thalami, there is no paralysis 

 of motion or sensation, although there may be a certain amount of weakness of the muscles 

 upon the side of the body opposite the injury. Experiments upon the inferior animals 

 have confirmed the conclusions to be drawn from these pathological facts. In frogs, 



