Anatomy. — "On the Relation between the Quantities of the Brain, 

 the N'eurone and its Parts, and the Size of the Body' ^). By 

 Prof. EuG. Dubois. (Communicated by Prof. H. Zwaardkmakek). 



(Communicated in the meeting of March 23, 1918). 



In an earlier communication ^) it was shown how the quantity of 

 the bi-ain in all the classes of vertebrates increases regularly with 

 the size of the body. F'rom species to species, and also from the one 

 sex to tlie other the quantity of the brain increases proportional to 

 the power 0.56 of the body weight; fiom individual to individual 

 of identical species, however, the quantity of the brain increases 

 proportional to only half so great a power, probably 0.22, as 

 computed from the data at disposal. 



It is not inconsistent with this regular proportionality that the 

 composition of the brain greatly varies in the different classes of 

 vertebrates, and is unequal, to some extent, even in different genera 

 — this proportionality concerning only animals of equal morpholo- 

 gical and physiological organisation, which differ oidy in the size of 

 their bodies. For them we may, indeed, expect that in this most 

 complicated organ the most intimate morphological and functional 

 conformity should obtain. 



We see, however, that the regular enlargement of the brain as a 

 whole is accompanied by a disproportion in the composition, even in 

 those animals which are equal morphologically and functionally, such 

 as were compared in each case. Most striking is this quantitative 

 alteration of the composition of the brain between those parts com- 

 monly regarded as more active, in opposition to other parts conside- 

 red to be more passive, i.e. between the substantia grisea, which 

 contains by far the most cell-bodies, and the substantia alba, which 

 consists principally of myelinated nerve fibers. Besides, the cell- 

 bodies aie more densely placed in the substantia grisea of small 



1) As the densities of the (airless) body and these constituents are pretty well 

 equal, all about the same small amount above 1 (H. Vierordt. Anatomische, 

 physiologische und physische Daten und Tabellen, 3 Aufl. 1906, p. 55 — 60), 

 "volume" and "weight", are sometimes indifferently used for each other in this 

 communication. 



2) These Proceedings. Vol. XVI. (1913), p. 647-668. 



