NEUROBIOTAXIS 283 
As long as the influence on right and left, or mdeed on all 
sides, be unequal, the object will change its position until the 
state of equilibrium is arrived at and the influence is the same 
everywhere. 
Let us now apply this to a charged field from which a stimulus 
irradiates and passes to a cell in the neighborhood. 
It will be clear, without anything further, that the outgrowth 
of the axis-cylinder in the current from the kathodic field to the 
anode has a state of equilibrium only in the course, that is, 
lengthways, of the current, i.e., in a collateral growing out 
perpendicularly or, where the growth stimulus proceeding from 
the irradiating current activated a cell in its. neighborhood, the 
latter must send out its axis-cylinder also perpendicularly from 
the source along with the current. This explains the peculiar 
fact of collaterals of axis-cylinders in the commencement of 
their course having invariably a strictly perpendicular position 
with regard to the axis-cylinder.*! 
The irradiation current which radiates sideways from an acti- 
vating axis-cylinder must naturally move in a direction perpen- 
dicular to this axis-cylinder. This is a physical fact that is only 
changed at the growing point of the activating axone. 
It will thus be seen that the presence of one axon, as well as 
the perpendicular position of the collaterals on the axis-cylinder, 
are but natural consequences of the perfect bipolar character of 
the current. Now the same holds good if two or more differ- 
ently running tracts, or differently placed centers, activate 
one cell simultaneously. We then may also expect only one 
axis-cylinder in the resultant line of the two current directions 
(two bio-electric fields), since only in this line the equal influence 
on both sides of the growing point, the energetic equilibrium, 
is realized. 
What will be the case if two or more activating centers are 
present not acting simultaneously? One of these activating 
centers has to be the first and causes the initial outgrowth. 
41 At the time when coloration and impregnation methods were not so ad- 
vanced as now, the differential diagnosis of collaterals and dendrites was some- 
times made on account of the perpendicular position of the latter on the axon. 
