Phcnnmena of ncurobiotaxis in Ihc optic svstem 



287 



phenomenon of neurobiotaxis, proving the different positions occupied 

 by those nuclei to be dependant on correlated stimulations. It herefrom 

 appears that next to tlie optic reflex-fibres, those belonging to the 

 eqíiilibrium system, have the strongest influence on the position of the nu- 

 clei of the eye-muscles. This relation of optic and vestibular reflexes 

 may be ascribed to the fact of th^ eye being originally a photo-static or- 

 gan (having hardly to do with the perception o{ images) zná photo-static 

 and gravistatic influences being the most important add always corre- 



Fig. 20 a. — Giant dendrites grow out in the direction of the centre from which the stimuli proceed (sti. cent.V 



Pig. 20 b. — The cell body itself (perikaryon) has shifted in the direction of the stimulation centre. The 

 dendrites have shortened, the axis-cylinder has enlarged. 



Fig. 20. — Shows that the outgrowth of the dendrites and the final shifting of the 



cell büdy itself takes place in a stimulo-petal direction, whereas the course 



of the axis-cvlinder is stimulo-concurrent. 



lated coordinants of space in life. \Ve may add to these as third 

 «detcrniinant-», the viuscle sensibility which probably also has a cen- 

 tre in the roof of the mid-brain (in fishes) and in lower parts of the 

 mesencephalon. 



To the roof of the mid-brain and on the corpus geniculatem laterale 

 the above mentioned law of neurobiotaxis has lately been applied by 

 Herrick and Obenchain. 



Whilst, till now in lampreys, the tectum seemed to be the only 

 terminus of the eye-nerve, sharks already show another optic centre, 

 which, proves to be the predecessor of the corpus geniculatem 

 laterale. 



