CENTRAL NERVOUS SYSTEM. 703 



The cortex of the frontal lobes has some connections with the nuclei of the 

 pons, and so with the cerebellum. The more recent experiments on the func- 

 tions of this region are by Bianchi l 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 are removed the change 

 is profound. On 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 sensations 

 and some paresis. Moreover, there is a hyperaesthesia 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 just 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 been 

 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 lobes 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. 



H. COMPARATIVE PHYSIOLOGY OF THE CENTRAL NERVOUS SYSTEM. 



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

 monkey, it will be of importance to briefly review the comparative physiology 

 of the central nervous system in vertebrates below the monkey. This system 

 in the lower vertebrates is usually composed of a very much smaller number 

 of cells than is found in that of man, and also cephalization, or the massing 

 of the elements toward the head and in connection with the principal sense- 

 organs, has gone on to a far less extent. 



It must not be thought, however, because it is the custom .to emphasize 

 the reflex activities of the lower vertebrates, and to show that these reflexes 

 can be carried out even by fractions of the spinal cord alone, that therefore 

 the spinal cord is particularly well developed in them. Comparative anatomy 

 shows in the lower vertebrates a simplicity in the structure of the cord quite 

 comparable with that found in the brain, and as we ascend the vertebrate 

 series both parts of the central system increase in complexity. In this increase, 

 however, the cephalic division takes the lead, and further, by means of the 

 fibre-tracts, the cell-groups in the cord are more and more brought under the 



1 Archives Italiennes de Biologic. 1895, t. xii. 



2 Archiv fur Anatomie und Physiologic, 1895. 



3 Ueber die Verrichtungen des Grosshirns, 1881. 



