610 



SCIENCE. 



[N. S, Vol. XIV. No. 355. 



tion to the fact that within this district 

 there are located two of his so-called, ' Ter- 

 minalgebiete,' or cortical areas, which at- 

 tain their functional powers at a later period 

 than those which lie around them, and which 

 may therefore be supposed to have specially 

 high work to perform. 



Without in any way desiring to throw 

 doubt upon the observations of these author- 

 ities, I think that at the present moment it 

 would be rash to accept, without further evi- 

 dence, conclusions which have been drawn 

 from the examination of the few brains 

 of eminent men that have been described. 

 There cannot be a doubt that the region in 

 question is one which has extended greatly 

 in the human brain, but the association of 

 high intellect with a special development 

 of the region is a matter on which I must 

 confess I am at present somewhat scep- 

 tical. 



But it is not only in a backward direction 

 that the parietal lobe in man has extended 

 its territory. It has likewise increased in 

 a downward direction. There are few 

 points more striking than this in the evo- 

 lution of the cerebral cortex of man. In 

 order that I may be able to make clear the 

 manner in which this increase has been 

 brought about, it will be necessary for me 

 to enter into some detail in connection with 

 the development of a region of cerebral 

 surface termed the insular district. The 

 back part of the frontal lobe is also in- 

 volved in this downward extension of sur- 

 face area, and, such being the case, it may 

 be as well to state that the boundary which 

 has been fixed upon as giving the line of 

 separation between the parietal and frontal 

 districts is purely artificial and arbitrary. 

 It is a demarcation which has no morpho- 

 logical significance, whilst from a physio- 

 logical point of view it is distinctly mis- 

 leading. 



D. J. Cunningham. 



[lb he concluded.l 



SCIENTIFIC BOOKS. 

 Die Partiellen Differential- Gleichungen der Mathe- 

 matischen Physik. Nach Riemann's Vorles- 

 ungen. In vierter Auflage. Neu bearbeitet 

 von Heinrich Weber, Professor der Mathe- 

 matik an der Universitat Strasburg. Braun- 

 schwieg, Druck und Verlag von Friedrich 

 Vieweg und Sohn. 1900, 1901. Erster Band, 

 pp. xvi + 506 ; Zweiter Band, pp. xi + 527. 

 The appearance of this new and greatly en- 

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 ence rests. 



It is a good sign of the times that many 

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The reader who may be unacquainted with 

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