468 DAVIDSON BLACK 
namentlich auch die Verlagerung des ganzen Leibes der Ganglienzellen, 
in der Richtung der maximalen Reizladung. 
2. Nur zwischen gleichzeitig oder direkt sukzessiv gereizten Stellen 
findet diese Dendriten- oder Zellenannaherung statt. 
3. Das Auswachsen der Achsenzylinder der sogenannten Zentral- 
motorischen Systeme wird nicht primir bedingt durch die motile 
Funktion gewisser Zellen, sondern ebenfalls durch synchron cder 
sukzessiv gereizte Gebiete (Schaltzellen v. Monakows). 
Since that time much work has been done by this author and 
his associates in extending and elaborating the field of these 
investigations, the importance of which, in view of their wide 
application to the problems of morphology, ontology and 
physiology of the nervous system, becomes increasingly evident.! 
It was my privilege to begin the present work under the 
direction of Dr. Kappers in the summer of 1914 with the object 
of adding to the data bearing upon the phenomena of neuro- 
biotaxis, by the study of new material recently acquired by the 
Central Dutch Institute for Brain Research. In accordance 
with this object the plan of treatment here adopted corresponds 
somewhat to that obtaining in Kappers’ communication of 1912 
(66) and the reconstruction charts of the motor nuclei in both 
cases are of the same dimensions. With regard to plotting these 
charts, it seems hardly necessary to point out that all charts 
can be made to correspond approximately in size for the sake of 
direct comparison because a difference in magnification does not 
in any way alter relative proportion. A description of this 
method of reconstruction and a discussion of its advantages and 
limitations will be found in Kappers’ earlier papers. A brief 
statement concerning the method is also set forth in the present 
article on page 474. 
Except in the case of Solea vulgaris, all the observations, 
drawings and reconstructions were carried out in the laboratories 
of the Central Dutch Institute in Amsterdam. My work 
being unavoidably interrupted in August, 1914, Dr. Kappers 
very kindly gave me the slides of the Solea series so that I might 
subsequently complete my observations on this form. 
‘ Reference may be had to the chief communications on the subject of Neuro- 
biotaxis in the appended bibliography. 
