CHAPTER XX. 



THE SIZE AND WEIGHT OF THE HUMAN BRAIN. 



THE size and weight of the Human Brain are capable of 

 being estimated in two ways, the one of which may be 

 termed 'direct,' and the other 'indirect.' 



We may, of course, measure and weigh the organ when 

 it is accessible, and an enormous amount of labour has 

 been expended in this direction especially by British 

 observers upon individuals of different ages, sexes, and 

 conditions. 



But when of the representatives of ancient peoples, of 

 foreign nations, or of savage tribes, all that the anatomist 

 possesses are mere brain-cases or skulls, he must, if he 

 would acquire definite notions as to the size and weight 

 of the organs which they previously contained, adopt some 

 uniform and carefully worked-out method for ascertain- 

 ing their exact cubical capacity. From the figures for 

 ' cranial capacity ' thus ascertained, the probable corre- 

 sponding Brain-weight will, when certain other data are 

 known, be dedncible with a fair amount of exactness. 



This latter ' indirect ' method of procedure is warrant- 

 able and capable of giving trustworthy results, because in 

 health the human brain invariably fills the skull to which 

 it belongs, except for the intervention of some thin mem- 

 branous envelopes with vessels and blood-spaces for which 

 definite allowances may ultimately be made. Much work. 



