NERVOUS CENTRES. (HUMAN ANATOMY. THE ENCEPIIALON.) 



663? 



TABLE III. 



MALES. 



FEMALES. 



From this table we are led to conclude that 

 the brain readies its greatest absolute weight at 

 an early age. The maximum is found in the 

 table at between 16 and 20; but, as Dr. Reid 

 states, it is plain that the apparent excess of 

 weight at this period over that for the next forty 

 years must have arisen from sources of fallacy 

 incidental to insufficient data. And in the 



group between 40 and 50, Dr. Reid states that 

 some brains much below the average weight 

 were found, so as to leave no doubt that the 

 diminution in the average weight in that group 

 was attributable to that circumstance. 



A decided diminution in the average weight 

 of the brain was noticed in females above 60 

 years of age; but, among the males, this was 

 not apparent until a later period. Upon this 

 point Professor Reid makes the following judi- 

 cious observation, which I am anxious to 

 quote as according with the views I have ex- 

 pressed at page 642 respecting liquid effusions. 

 " We certainly did expect," he says, " also to 

 find a similar diminution in the average weight 

 of the male brain above 60 years of age, for 

 we are perfectly satisfied, as the tables contain- 

 ing the individual facts will shew, that we more 

 frequently meet with a greater quantity of 

 serum under the arachnoid and in the lateral 

 ventricles in old people than in those in the 

 prime of life. We are also satisfied from an 

 examination of the notes we have taken at the 

 time the brains were examined, that a certain 

 degree of atrophy of the convolutions of the 

 brain over the anterior lobes, marked by the 

 greater width of the sulci, was more common 

 in old than in young persons. We have, how- 

 ever, frequently remarked these appearances in 

 the brains of people in the prime of life who 

 had been for some time addicted to excessive 

 indulgence in ardent spirits." 



The ratio between the weight of the body 

 and that of the brain is greater in early age than 

 at the subsequent periods. The following pro- 

 portions were obtained byTiedemann, in infants 

 just born. In two boys the proportion of the 

 brain to the body was as 1 : 5.15 and 1 : 6.63, 

 and in two girls as 1 : 6.29 and 1 : 6.83. The 

 following table gives Professor Reid's results 

 from the examination of 92 bodies. 



TABLE IV. 



Relative weight of entire body to encephalon, cerebrum, cerebellum, cerebellum with pons 

 Varolii and medulla oblongata, in 92 bodies. 



Une of these was above 70 years of age. 



