THE MOTOR NUCLEI OF THE CEREBRAL NERVES IN 
PHYLOGENY: A STUDY OF THE PHENOMENA 
OF NEUROBIOTAXIS 
PART I. CYCLOSTOMI AND PISCES 
DAVIDSON BLACK 
From the Central Institute for Brain Research, Amsterdam, Holland, and the 
Anatomical Department, Medical School, Western Reserve University, 
Cleveland, Ohio 
FORTY-TWO FIGURES 
CONTENTS 
introductlonkassen ee nee BS lai: ee a oA eae aed 467 
LOirae) keshrras cas 4 ak ao as Sciers he ah aR RES 2c ary DOU pe PL ee OE 470 
Motonmuclerines dellostomaydombeyies- pe secrete cae eis ei ere 470 
DISCUSS O Tear Rete ee a ets tees. iss, zt <M mse/cODRG sc a ae 476 
Sel Sie Wee eee sexe Se ieee cin ne Re ees ce Ns 5 5 oN RE TYR o, con Re eS EE 485 
Motorsnucleiminuselachenmaxaimancn. 22 eae sare Mee nnriat a caeriee er: 485 
DIS CLISSTO Mtr 3. yoepcr a eae ies Sl «Sid dk eas cinco fot cee ee 494 
CLTNOTE Me eee Se oS Soe tS coeiie) Sia ee RE RREORS See cokcc A oere nn e nOiae 502 
Motonnuclemnerolyodonispathul aes. seeo seer ee eee eee areca 502 
ID ESYOLOVSTSHIG) be Braet hes GRRE rato i, «i Renata yen ERR ORB 1! coh pr 2 SP EPR NEES cE alata 509 
UNIX OPS) Weg bees ok eat ee a 8s Se eet Le Dil Rae eA 8 ho eer Ae 522 
Motor nuclei in Ameiurus nebulosus and Solea vulgaris................. 522 
DTS USSU O MD yee See ce IA rc ots OW et OAS che Ik ote ae aaeR SR Rees oan 535 
(omni STOM A Pee eee Tsetse EA Stee Pest ad hg hcl eNere or ME ce aca eae’ 555 
J Ey ibyemeren Rrra) TeX |= 5 rere ee OR eae ces cc RR at STR Pn Coach, reser ee 559 
INTRODUCTION 
In 1907 Kappers first directed attention to the significance 
of the phylogenetic displacements of the motor nuclei of the 
medulla. In 1908 (60, p. 521) he enunciated more definitely 
his doctrine of Neurobiotaxis and set forth the following con- 
clusions deduced from the study of nuclear migrations: 
1. Wenn in dem Nervensysteme am verschiedenen Stellen Reiz- 
ladungen auftreten, so erfolgt das Auswachsen der Hauptdendriten, 
467 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL, 27, NO. 4 
