Phenomcna oí neurohiotaxis in thc optic System 285 



disappeared on the gth day. The fibresystems, reaching the nucleus in 

 this stage, make it probable — that peculiar relations of engrammatic sti- 

 muli (newly outgrowing central axons) are the cause of this shifting of 

 some elements by which a part of the root fibres acquire a crossed 

 origin. (Comp. Ca/afs quotation on the 2.^ pagc of this papen. 





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V\'¿. 18.— Diaorammritic representation of the developrncnt of llie Xuii. Kdins^cr- 



Westphal (gray) in the vertébrate series and the concrescence of the hind part of 



the III nucleus (black) in Carnívora with the formation of a central nucleus of 



Perlia, growing in between the Edinger-Westphal nuclei. After Brouwer. 



In mauíinals. the nucleus oculo-motorius is subject to peculiar altera- 

 tions, connected with the development with convcrgency and accoinnwda- 

 tiojí^ which — as is known — cooperate in active binocular visión. 



Perlia s central cell-group, connected with coiivcrgoicy and lying in 

 the raphe, makes its first appearance as a distinct group, in higher mam- 

 mals, the Carnivores [Brouzver), where it is seems to origínate from a fusión 

 of a part of the cellgroups, belonging to the recti interni, the muscles of 

 convergency (^fig. 1 8). 



