NEUROBIOTAXIS 281 
This substance perhaps also helps to explain the relatively 
late formation of the dendrites, since the nuclein substance does 
not appear until late in the cell body in the form of Nissl bodies 
which, originating from the chromatin of the nucleus (Scott) ,38 pass 
through the nuclear membrane in a stage of development when 
the axis-cylinder has already completed its growth over a cer- 
tain extent, and has even become fairly considerable. 
Cajal*® did not find this substance before the time when the 
dendrites start to grow out. Consequently when this substance 
is present in the protoplasm we observe a tendency in the pro- 
toplasm to shift in the direction of the stimulated field (the 
kathode) and to be followed by the contraction of dendrites and 
finally the shifting of the whole perikaryon in the direction of 
the stimulation field, i.e., in the direction of the negative electric 
field. 
The difference of time between axis-cylinder outgrowth and 
dendrite formation thus would be a result of the general anodic 
kataphoretic character of genuine albumen and lecithin, the 
alkaline reaction of the pericellular lymph and the quantity of 
KCl salt present around the young cell and, further, the greater 
conductivity that this gives to the axis-cylinder on one hand, 
and on the other hand the late appearance of the nucleic acid 
derivatives in the protoplasm. 
It cannot surprise us in this respect that only small dendrites 
are found on those cells whose chromatin is still entirely in the 
nucleus (granular cells), and that the smallest quantity of 
nuclear chromatin is found in those cells whose dendrites have 
developed most (motor cells, reticular cells and others). 
Only the question would remain why the alkaline reaction 
of the body lymph, which is the same around the axis-cylinder 
and the dendrite, does not interfere with a kathodic outgrowth 
of the latter and this fact seems to prove the truth of the opinion 
38 Scott. On the structure, microchemistry, and development of nerve cells 
with special reference to nuclein compounds. Trans. Canadian Institute, vol. 6, 
part 142, p. 405, Dec., 1899. 
39 Cajal. Textura del sistema nerviosa del hombre y de los vertebrados, 
tomo 1, p. 528, Madrid, 1904. 
