262 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



functions of this region arc by Bianchi ' and Grosglik, 2 the former on monkeys 

 and dogs and the latter on dogs alone. 



These experimenters found that the removal of one frontal lobe is com- 

 paratively insignificant in its effects, while when both arc removed the change 

 is profound. < )n removing the frontal lobe on one side only there is no dis- 

 turbance of vision, hearing, intelligence, or character. There do occur both 

 sensory and motor disturbances, but these are for the most part transient. 

 On the side opposite to the lesion there is in the limbs a blunting of all sen- 

 sations and some paresis. .Moreover, there is a hyperesthesia combined with 

 a paresis of the muscles of the neck and trunk which move these parts 

 away from the side of the lesion. 



These several effects of the operation tend to pass off, and if then the 

 remaining frontal lobe be removed from a dog or monkey, not only do the 

 symptoms ju>t described appear on the other side of the body, but still more 

 fundamental changes occur. A ceaseless wandering to and fro, such as 

 Goltz 3 observed, in those dogs in which the anterior half of the brain had 

 lien) removed, characterizes the animals; curiosity, affection, sexual feeling, 

 pleasure, memory, and the capacity to learn are at the same time abolished, 

 and the expressions of the animal are those of fear and excessive irritability. 

 That, therefore, the frontal lobe- play an important role in the total reactions 

 of the central system is amply evident, but this by no means justifies the 

 conclusion that they are the seat of the intelligence. 



F. Comparative Physiology of the Divisions of the Encephalon. 



For the better comprehension of the conditions found in man and the 

 monkeys, it will be of importance to briefly review the comparative physi- 

 ology of the parts of the encephalon in vertebrates below the monkeys. The 

 encephalon in the lower vertebrates is usually composed of a very much 

 smaller number of cells than is found in that of man, and also the massing 

 of the elements toward the cerebral cortex and in connection with the princi- 

 pal sense-organs has gone on to a tin - less extent. 



For the determination of the functions of the several parts of the enceph- 

 alon it i- possible to employ in animals the method of removal as well as the 

 method of stimulation. The doctrine of cerebral localization was at one time 

 crudely expressed by the statement that a cortical centre was one the stimu- 

 lation of which produced a given reaction, and the removal of which abolished 

 this same reaction. Goltz soon showed that in the dog the removal of even 

 an entire hemisphere did not cause a paralysis of the muscles on the opposite 

 side of the body, although others had shown that a stimulation of certain 

 portion- of the cortex of the hemisphere would cause the muscles to contract. 

 It was argued, therefore — and quite rightly — that the cortical centres of the 

 dog did not completely answer to the definition. 



1 Archives italiennea de Biohgie, 1895, t. xii. 



2 Archiv fur Anatomic mid Physiologic, 1895. 



3 Ueber dieVerichtungen des Grosshirns, Is- 1. 



