NEUROBIOTAXIS 287 
A closer approach of the two neurones, a contiguity, will be 
the result. That this will not (or not easily) occur if the grow- 
ing axis-cylinder reaches a cell in rest, may result from the fact 
that this passive cell, or neurone, is not in that strongly electrolyt- 
ically dissociated condition and possesses no considerable electri- 
cal potential difference from the surroundings. Or to put it 
otherwise, the passive, non-stimulated cell has thus no other 
significance for the growing axis-cylinder in its vicinity but that 
of a corpus alienum, 1.e., it is fairly indifferent to it. 
As far as concerns the fact that axonic endings never com- 
municate with axonic endings and dendritic endings never with 
dendritic endings, no further explanation is necessary from the 
standpoint of polar electrolytic conditions accepted here, which 
necessarily implies that homonymic outgrowths do not act on 
each other. 
FASCICULATION OF AXONS. IMPROVEMENT OF THE NERVOUS PATH 
One might ask in this connection why nerve fibers, if homonymic 
forces repel each other, tend to group together in fiber-tracts or 
bundles, as we always see even if they do not end on the same 
level (as the pyramidal tracts). 
This process may, however, be analogous with the mono- 
axonism, that an axon shall tend to place itself in the way of 
the current, and if now such a current reaches a pluricellular 
center it is not strange that the chief resultant line for the out- 
growth of one cell is also the state of equilibrium for the out- 
growth of the other adjacent cells. The orientation of a number 
of nerve-fibers (axons) from a cell group into one bundle‘ 
may be no more than a repetition of the same process concerning 
the neurofibrils in one axon, which tend to a state of central 
equilibrium in the axis of the neurite. 
Perhaps also a sort of magnetic field formed by equally run- 
ning currents may exercise an attraction here. Such a magnetic 
field is also present around colloidal threads. 
45 Perhaps also a sort of magnetic field formed by currents running parallel 
exercises an attraction here. 
