57:43 ill an otlicr. in the liiiiiiaii brain Danilkwsky found as an 

 average j-esnit of several experiments tills relation lo be 39 : 61. 



Tliese results are liighlj interesting- and it is a great pily that 

 Danilewsky has not continued this work and that the onl}^ results 

 which he mentions concern two subjects with such a different develop- 

 ment of the nervous system. I will however call attention to the fact 

 that in the larger of the two — man — the author found a much 

 greater relative amount of white substance (llVo more) than in the 

 smaller. 



Intending to examine only one of the factors that may 

 intluence the relation between white and grey matter: the size of 

 the brain, I have thought it convenient to study corresponding 

 regions in small and large representants of the same orders, thus 

 avoiding as much as possible the influence that might be exercised 

 by differences in evolution. I found the spinal cord to be the 

 most fit for this purpose on account of the circumscript form of its 

 constituents and since the cervical cord of a large amount of material 

 was at my disposal in the Central Institute for Brain Research I 

 have made use of this. 



That the brain of large and small animals of the same sort shows 

 a difference in the quantitative relation of the above mentioned 

 constituents was remarked already by Brandis ^) in 1893 and in- 

 dependently of this author by Ernst de Vries (I.e.) 



-The former found that in the spinal cord of a large bird (Anser) the 

 white matter was not only absolntely, but also relatively larger than 

 in a small bird (Regulus, see tig. 2). 



It seemed useful to me to test this occasional remark by a 

 larger amount of material chosen from all classes of vertebrates 

 and from as many orders of mammals as were fit for this research. 

 My material contained : 



Two sharks. 

 Two chelonia 

 Three lacertilia 

 Four birds 

 Three rodents 

 Two ungulates 

 Two carnivoia 

 Four platyrrhine apes 

 One elephant. 



^) Untersuchungen iiber das Gehirn der Vügel. Archiv. f. mikr. Auutomie. Bnd. 

 •iJ, 1893. pag. 177. Theil i. 



