622 PHYSIOLOGY CHAP. 



by psychical symptoms. Welt (1888) compared 59 cases of 

 different lesions of the frontal lobes: only in 12 cases was 

 there any mental disturbance or change of character. Recent 

 observations have contributed nothing in support of the old 

 .hypothesis that intelligence depends particularly upon the pre- 

 frontal lobes. Eoncoroni (1911), from a careful review of the 

 most recent clinical cases, concludes that lesions of the pre-frontal 

 lolies do not produce motor paralysis nor sensory alterations, the 

 most characteristic symptoms being impulsiveness or irritability, 

 a tendency to irrelevant witticisms, amnesia in regard to particular 

 words and acts, alterations in handwriting, apraxia, ataxy, and 

 alterations or loss of the power of performing certain voluntary 

 acts. The absence of sensory and motor symptoms with lesions 

 in the pre-frontal lobes agrees according to Eoncoroni both with 

 the experimental facts and with the cytotectonic observations of 

 Brodmann, as well as with the anatomical relations of the 

 pre-frontal lobe. Eoncoroni in conclusion declares against the 

 hypothesis that the highest intellectual faculties are located in 

 the pre-frontal lobes. 



When, on the other hand, we consider Flechsig's great posterior 

 association area we see at once that both physiological evidence 

 and the facts of morphology and anthropology point to the special 

 importance of this region in mental functions. 



Gk>ltz' experiments upon dugs in which the whole posterior 

 half of the hemispheres were removed are of great importance in 

 estimating the value of subsequent investigations. He saw that 

 dogs which were lively and active before this operation became 

 quiet and apathetic. Even more striking than this change of 

 character was the marked diminution of intelligence : the animals 

 behaved as if they were imbecile or demented. 



We observed practically the same signs of grave mental 

 disturbance in dogs from which the whole cortex of the parietal 

 lobe, or the parieto-occipital, or the parieto-temporal region, was 

 removed. Removal of these regions leads to serious disturbance 

 of all sensory function, while lesions of no other part of the 

 cerebral cortex of the dog produce such complex effects, which of 

 course imply profound mental degradation. 



On comparing the four diagrams representing the visual, 

 auditory, tactile, and gustatory spheres in the dog (Luciani and 

 Seppilli, Figs. 306, 307, A, B, C, D), it is at once evident that each 

 sensory sphere, besides its own area, overlaps and partially fuses 

 with those around it. This common area is the parietal lobe, 

 more precisely Munk's ^'sphere (Fig. 296), which we regarded as 

 the most important region of the dog's hemisphere, as the centre 

 of centres, on which the normal association of percepts and their 

 memory images depend. 



The recent work of 0. Kalischer (1907) on the psychical 



