2O2 THE GROWTH OF THE BRAIN. 



been also asserted that in the criminal brain the fissures 

 ran together in such a manner that the channels formed 

 by them are more continuous than in the case of normal 

 individuals. It requires still to be proved that this is 

 characteristic of the brains of this class, for non-criminal 

 brains differ very markedly in the degree to which the 

 fissures are confluent. In view of what has been said 

 just above, this greater or less confluence of the fissures 

 may be interpreted in various ways, and while confluence, 

 so far as it goes, indicates a large area of the cortex, it 

 may have quite different meanings in large and small 

 brains. 



By various devices the extent of the folded surface ot 

 the hemispheres has been measured. These measure- 

 ments have been made either directly or by determining 

 the volume of the cortex, and then, assuming that it had 

 an average thickness, by making an estimate of its 

 extent. Among the earlier observations were those by 

 Wagner, 1 who undertook to determine the area of the 

 cortex in the brains of Fuchs, the pathologist, and Gauss, 

 the mathematician, and to compare this area with that 

 found in the brains of a labouring man and a woman of 

 ordinary intelligence. Unfortunately this determination 

 was not made until after the brains had lost from 

 about 27 to 40 per cent, in weight by their preservation 

 in alcohol, and had consequently undergone some dimi- 

 nution in volume, so that the figures given for the areas 

 in these several cases apply to the brains after this treat- 

 ment Some slight data are available by which a rough 

 correction of these results can be made (Donaldson), and 

 thus corrected, 2 the weight of the cortex appears in 

 Table 47. 



1 H. Wagner, Massbcstimmungcn aer Oberfldche des %rossen 

 GehirnS) Inaug. Diss., Gottingen, 1864. 



2 Donaldson,/^wr. of MorphoL, 1894 



