142 Journal of Comparative Neurology. 



however, that Hammarberg's method of staining the cells (alco- 

 hol hardening, followed by methylene blue) did not bring out 

 the dendritic processes, and hence that the volume of the cells 

 determined from his preparations is too small. This is perfectly 

 true, and it is therefore desirable to determine how much of the 

 cell substance has been thus overlooked. In making the cor- 

 rection for the dendrons which were not stained by the methy- 

 lene blue, some caution must be exercised. To obtain a com- 

 plete picture of the dendritic branches, we usually refer to a 

 successful Golgi preparation. It must be remembered, how- 

 ever, that the diameters of the dendrons are increased in such 

 preparations beyond their normal size, owing to the incrusta- 

 tion of the silver chromate deposit, and for this reason the true 

 volume of the dendrons is not nearly so great as the silver 

 chromate picture would suggest. From a preliminary survey, 

 I conclude that 2 ^ will represent the proportional volume of 

 the cortical cell bodies, including all the dendrons. ' 



At the moment, an exact statement concerning the volume 

 of the cell bodies in the remaining portions of the encephalon 

 cannot be made. In this remaining portion, including as it does 

 all the white substance beneath the cortex, the proportional 

 volume of the cell bodies" is probably much less than the vol- 

 ume of those in the cortex itself. It thus appears that the 

 small volume of the cell bodies is a feature of the entire en- 

 cephalon.^ 



The volume of the 9,200,000,000 cortical cell bodies be- 

 ing very small, it can be readily shown that their weight is also 

 very small. ^ 



^ I further assume that this estimate of 2^;^ is large enough to include also 

 the terminals of the axones which end about the dendrons. 



' By this is meant the cell bodies in the striata, thalami, quadrigemina, 

 cerebellum, pons and central gray substance. 



^ The estimate that the cell bodies of the entire encephalon have a volume 

 of 2^, probably errs on the side of excess. 



* In translating the proportional volume of the nerve cell bodies into pro- 

 portional weight, no correction is made for the fact that the specific gravity of 

 the cell bodies is slightly less than that of the cortex of which they form a part. 



