76 
Proceedings of the Royal Society of Edinburgh. [Sess. 
Sherrington * states that he is unable to find any unequivocal degenera- 
tion as a result of large lesions of the post-central gyrus in the anthropoid. 
Vogt,f working on lower apes, arrives at results differing from those of 
the last named author. He finds degenerated fibres in the internal capsule 
as a sequel to lesions whether made anterior or posterior to the fissure of 
Rolando, but the position of the degeneration is different in the two cases. 
The degeneration in the internal capsule, resulting from ablations in the 
ascending frontal convolution, finds its posterior limit in horizontal section, 
according to this observer, at the level of the oral end of the nucleus 
ventralis lateralis posterior, while ablations of cortex in the ascending 
parietal convolution give rise to degeneration posterior to this level. The 
author brings forward evidence in support of his view that the line 
separating the areas in the internal capsule presenting degeneration in the 
two cases forms an important boundary between two distinct systems of 
fibres. 
Such divergence m results, as regards paralysis and degeneration, 
produced by lesions in front of and behind the fissure of Rolando, are in 
favour of our ascribing different functions to the ascending frontal and 
ascending parietal gyri. 
We have next to consider what support, if any, for our views of the 
extent of the motor area can be drawn from a study of the myelination of 
the nerve fibres. 
It has been shown that the ascending frontal and parietal convolutions 
are alike characterised by early development of myelination. Flechsig^ 
depicts the ascending frontal and the anterior part of the ascending parietal 
convolutions in man as one area, whose posterior boundary thus lies near 
the middle of the ascending parietal convolution. The anterior boundary 
of this area corresponds nearly with the anterior limit of the Rolandic 
excitable cortex, but the posterior boundary does not coincide with any 
dividing line arrived at by the method of electrical excitation. Further, 
the posterior boundary does not correspond, as we shall presently see, with 
any change in the histological structure of the cortex, but lies near the 
middle of an area which has been delimited by histological methods and 
named by Brodmann § the area culminis. This area culminis corresponds 
to the caudal part of the post-central area, together with the oral part of 
the intermediate post-central area of Campbell. || 
* The Integrative Action of the Nervous System, p. 277. t Loc. cit. 
J Gehirn und Seele, Leipzig, 1896, Taf. iv. 
§ “ Beitrage zur histologischen Legalisation der Grossliirnrinde,” Journ. f. Psych, u. 
Neurol., 1903-1906. “ Diskussion,” Neurol. Centralbl., 1904, p. 669. See also Vogt, loc. cit. 
|| Histological Studies on the Localisation of Cerebral Function, Cambridge, 1905. 
