— 134 — 
minent in some small masses, which are especially ventrally situated 
on each side of the nerve-cord, and which have a more minute and 
granular appearance than the rest of the dotted substance. 
In longitudinal section such masses will be found to occur 
especially near places where peripheral nerves issue. Fig. 66 represents 
such a place tåken from a longitudinal section. a a are parts of 
the central longitudinal septum, dividing the ventral nerve-cord longi- 
tudinally into two lateral cords (cf. fig. lo, (i). Smaller and larger 
nerve-tubes {tt^\ U\ tt) are seen passing the septum, from one side 
of the nerve-cord to the other, a great many of these small nerve- 
tubes {tf) seem to pass to the origin of the peripheral nerve, 
which origin lies to the left of the illustration. Some large nerve- 
tubes [pt, pt) pass to the same peripheral nerve. Amongst the 
longitudinal nerve-tubes smallish [t) as well as largish (It) tubes may 
be seen. The nerve-tubes running transversally between these 
longitudinal nerve-tubes are, also, of different sizes. Besides nerve- 
tubes, neuroglia-fibres with transverse courses also occur, and they 
are often difficult to distinguish from nerve-tubes. Such transverse 
neuroglia-fibres may, for instance, be distinctly seen in the dotted 
substance on the left hand side of fig. 67. 
Neuroglia-nuclei occur somewhat sparingly in the dotted sub- 
stance of the ventral nerve-cord of Nereis. They are oblong, have 
a granular appearance, and are generally longitudinally situated in 
the sheaths of the longitudinal nerve-tubes (vide fig. 66, n). They 
are, however, also transversally situated in the sheaths of transverse 
nerve-tubes (vide fig. 66, n^). 
To find the origin and course of the various tubes constituting the 
dotted substance has been very difficult, as I have not yet succeeded 
in obtaining any staining by the chromo-silver method in the nervous 
system of these animals. As far as I have been able to penetrate 
by help of the common staining with hæmatoxylin etc. (which has 
before been described) I believe, however, to have found that the 
constituents of the dotted substance have chiefly (if not wholly) the 
same origin in these animals as they have in Homarus. 
I have found ganglion cells with nervous processes wich were 
directly transformed into nerve-tubes, but from which side-branchlets 
were given off" (vide fig. 44). I have, however, not been able to- 
trace such nerve-tubes (direct continuations of nervous processes) 
into peripheral nerves; those which I have observed, have partly 
had a longitudinal course in the nerve-cord. 
I have also found ganglion cells with nervous processes, which 
