— 40 — 
described a direct origin of the tubes in cells, but at the same tune 
have also described an indirect origin as being present, Walter, 
SOLBRIG, BOHMIG and HALLER even suppose this to be the prevalent 
mode. 
Walter desribes the indirect origin as being produced by 
interposed multipolar cells, whilst the other writers presume a more 
or less fibrous or reticular substance as being the interposing me- 
dium ; this substance is principally formed by processes from the cells. 
Haller and Hans Schultze (as will be mentioned later) de- 
scribe both modes of indirect origin. 
Upon several occasions I, myself, have described an indirect, 
as well as a direct, origin of the nerve-tubes and supposed both 
modes of origin to be present to a somewhat similar extent, as, in 
my opinion, the nerve-tubes having a direct (never isolated as 
most writers maintain) origin should be motoric ones, whilst those 
with an indirect origin should be of a sensitive nature. 
Amongst those who maintain an indirect origin of the nerve- 
tubes from a granular-fibrous mass, and, as a rule, deny the existence 
of a direct origin, the following writers may be specially named: 
Leydig, Waldeyer, Hermann, Hans Schultze, Krieger, Vignal, 
Pruvot, Viallanes, f. v. Wagner Some of these, e. g. Leydig 
and Waldeyer, admit a direct origin to occur quite exceptionally. 
Leydig is the first writer who has given a somewhat detailed 
description of the central mass of the ganglia. He calls it 
»Punktsubstanz« and characterises it as a »netzformig gestrickte 
Gewirr feinster Faserchen«. This »Punktsubstanz« receives on one 
side the branching processes of the ganglion cells (these loose them- 
selves into the fibrous substance) on the other side it gives origin to 
the peripheric nerve-tubes. 
This not very detailed description by Leydig has beensupplemented 
by very few scientists. Most writers seem to be satisfied with it, 
they use the name without entering more closely upon this difficult 
subject, and do not try to define the structure of the central mass 
more exactly. W^^LDEVER characterises it as a » Gewirr feinster Fa- 
den«, which should originate principally in the division of the cell- 
processes. 
BuCHHOLZ (1. c. 1863) calls this mass »jenes feinste Faser sy stem, 
welches iiberall innerhalb der Nervencentren verbreitet ist.« He has, in 
my opinion, in many respects, arrived at a very correct view, which is 
scarcely surpassed by any other writer. The fibrillæ of this »Faser- 
system« are extremely slender. »Die Ursprungsweise derselben ist 
nun, wie angedeutet, eine doppelte ; einmal nåmlich gehen sie, wie 
