THE WEIGHT OF THE BRAIN AND SPINAL CORD. 87 



both of which extreme observations were made on 

 brains of small weight. The mean weight of the pia in 

 the case of 133 females was found to be 48*7 grammes, 

 and in the case of 273 males 55*8 grammes. Th. v. 

 Bischoff has determined the weight of the pia as from 

 25 to 40 grammes. 1 In the insane Morselli 2 finds the 

 weight of the pia and fluids to be almost double that 

 found in normal persons. 



The cast of the ventricles as made by Welcker 

 displaces 26 cu. cm. of water, so that the fluid filling 

 such a cavity would weigh a trifle over 26 grammes. 

 From these results some notion of the part played by 

 the ventricular fluid and the pia is to be obtained. 

 There are numerous other records relating to the dura, 

 but they differ so widely that evidently they should not 

 be compared with one another. Variations in the pro- 

 portion of these non-nervous constituents can produce 

 noticeable discrepancies when single brains are com- 

 pared, but as soon as average weights based on series of 

 twenty or more specimens are taken the disturbance 

 caused by them ceases to be important. 



At one time it was my purpose to combine all 

 existing data, and from the broader basis thus estab- 

 lished to, test the validity of conclusions current in this 

 field. It soon became plain, however, that for a number 

 of reasons the observations made by different observers 

 using dissimilar methods and working with various 

 races, were .not in themselves homogeneous enough to 

 bear fusing without very important corrections. It has 

 therefore been deemed best to discuss the question 

 before us simply by the aid of a few of the best series 

 of observations. 



In Table 5, already given, the brain is recorded as 



1 Bischoff, Das Hirngeivicht des Menschen, 1880. 



2 Morselli, Rev. de rAnthropologie, t. i, 1890. 



