296 



C L'. Aricns Kappers 



¡ntramedullar position, which in the course of their evolution changes 

 into an extra-medullar one, which in higher animáis is already eífectua- 

 ted in the «anlage». 



The outward migration in Amphioxus seems to be proved by the fact 

 that certain fibre-tracts, lying in the way of these cells, sometimes have 

 an outward curve, pointing to the traction etTected by the passing cells, 



SupranieduU. scns. ( ian^liencellb. 



•?*^: 



IntratiieduU. sens. Gan^liencells. 



^5$/!'.. 







Vig. 24. — Intramedullar and supramedullar sensory roots-celLs in Lophius 



piscatorius. 



as has been pointed out by JoJinston. \Ve apparently find here a gra- 

 dual shifting of the cells towards tlie pcriphery w hich means a shitting in 

 the direction of the stimulus, i. e. a. case of neurobiotaxis. 



In highef fishes, Amphibia and some Reptiles, \ve still find in the 

 substance oí the spinal cord, intra-medullar spinal ganglion-cells, either 

 in larval stages only, or sometimes also in the adult, the so-called cells of 

 Rohon and Beard, which are often transitory cells, because of their disap- 

 pearance in the adult. 



