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Franklin P. Mall. 



expansion of the brain, due to both its age and its size. So it 

 is possible for the frontal lobe at first to expand more rapidly 

 than the rest of the brain, and later to shrink more quickly. This, 

 of course, would affect the percentage of the frontal lobe and is 

 a source of error to be reckoned with. The presence of a second 

 preservative like common salt, alum or carbolic acid, which was 

 used in a number of my specimens, is also to be taken into account, 

 for they influence very much the change of volume of the brain. 



In order to test this question I weighed the pieces of 5 brains a 

 number of times during a period of nearly a year and found that 

 there was much fluctuation in the brain weight, but the percentage 

 value of the frontal lobe remained very constant, usually within 

 one-half of one per cent. 



The figures are as follows. The first weighing was made as soon 

 as the brain was fairly hardened at the end of about a week, so the 

 weights of the parts when fresh were not obtained. Those marked 

 with a star (*) are the weights recorded in the Table and in the 

 Figures. 



No special care was taken to keep the strength of the formalin 

 constant, in fact it was often changed, and this accounts for the 

 fluctuations in the weight of the whole brain. In all cases the parts 

 of each brain were kept together in a single jar in order to subject 

 them to the same strength of formalin from weighing to weighing. 



