312 



far as lliis relation in rciianl to tlie evolutionary standpoint of mam- 

 mals is concerned. It is even difficnlt to tind a trustworlh) method 

 for measuring this rehition and still more difficult to explain an 

 eventual result. Doing so there would be a considerable chance to 

 leave the Held of exactness and to grasp in the darkness of theories. 



The man}- factors that may act a part in this relation have been 

 mentioned by Ernst de Vries '). 



Several other authors (Sneli. '), Weber '), Dubois ') have demon- 

 strated that there exists a relation between brainweight and the 

 place occupied by the animal in the evolutional series, but specially 

 between the weight of the brain and that of the body in such a 

 sense that small animals have as a rule a greater relative brain- 

 weight than large aninuils of the same order. 



From this appears that at least two factors, the evolutionary stage 

 and the size of the animal have an influence on the mass of the 

 brain. 



Equally in the study of the relation of grey and white matter 

 different factors have to be considered. 



The author intended to study only one of these factors, viz. the 

 intluence of the size of the brain on the relation between white 

 and grey matter. 



This relation has very rarely been examined with exact methods. 



The first who tried to obtain really exact results was Danilewsky ^), 

 wlio made use of the physical method of Archimedes to define the 

 quantitative relation of two constituents of a mixture, by measuring 

 the specific weight of each of the constituents, and then the specific 

 weight of the mixture. 



With this method Danilewsky found the relation between grey 

 and white matter in a dog's brain to be 50 : 50 in one case and 



1) Dr. E. DE Vries, Das corpus sti-iatum der Siiugethiere. Anatom. Anzeiger. 

 37sler End. 1910. p. 386. 



~) Snell, Die Abhangigkeit des Hirngewichts luid die geistigen Fahigkeiten. 

 Archiv f. Psychiatrie. Bnd 23, 189^2. 



3) Weber, M. Vorsliidien über das Hirngewichl der Saugelhiere Festschrift f. 

 Gegenbiur 1896. Weber, M. Over het Hersengewicht der Zoogdieren. Kon. Aka- 

 demie v. Wetensch. te Amsterdam, October, 181'6. 



•^) Dubois, E. Ueber die Abhangigkeit des Hirngewichts von dei' Kürpergrösze 

 bei den Saugelhieren Archiv. f. Anthropologic, Bnd 25, 1897. 



s) Danilewsky. Die quanlitativen Beslimmungen der grauen und weiszen Sub- 

 stanzen im Geliirn; Centralblatt fur die medizinischen Wissenschaften N^. 14, April 

 1880 p. 241. 



The results here referred to were already mentioned by the author at the 

 congress of naturalists in Gharkow, 1878. 



