348 



THE SIZE AND WEIGHT 



however, still remains to be done before the amount of these 

 allowances or their range of variation for persons of different 

 ages, sexes, and races can be accurately determined ; and 

 the same may be said in reference to differences in the size 

 of the 'lateral ventricles,' since either excess or defect of 

 the usual space thus appropriated may also occasionally 

 intervene as a disturbing condition, tending to vitiate an 

 ' indirect ' estimation of Brain-weight. Though it is 

 true, therefore, that certain relations ought always to 

 obtain between * cranial capacities ' and Brain- weights, 



these cannot be said to 

 have been yet deter- 

 mined except in a mere 

 preliminary and tenta- 

 tive manner. According 

 to the general rule laid 

 down by Dr. Barnard 

 'Davis a deduction of 

 about 15 per cent, from 

 the capacity of the Cra- 



FIG 131. One side of the Skull removed, show- nium gives the 'capacity' 

 ing the Dura Mater with its vessels enveloping ., , T - ) 14? 



the Brain. (After Hirschfeld and Leveille.) a, Ol the .brain, and fr 



be 



Commencement of the great longitudinal Venous -f-Jjjg fo 



Sinus, which is continued backward towards 6. 



Close to this is situated the meeting-point of deduced by Calculation. : 



several Venous Sinuses. Both the < indirect 



and the 'direct' methods are of great utility, and either 

 may be had recourse to by the experienced investigator 

 according as Skulls or Brains present themselves for 

 examination. Each method offers certain advantages, but 

 on the whole it may be said that if Brains were always 

 accessible, we should probably hear less on the subject of 

 'cranial capacities.' The 'indirect' method seems well 



* See " On the Weight of the Brain in the Different Eaces of 

 Man," PMlos. Trans., 1868, pp. 506 and 526. 



