— 125 — 
are, however, all of them, smaller than those small nerve-tiibes, and 
they have, to a certain extent, a rather uniform size, with their dia- 
meter about the same as that of the common primitive tubes of 
the nerve-tubes (vide in t nt^). There are, also, a great many ex- 
tremely minute meshes or tubes which are even smaller than the 
smallest primitive tubes I have been able to observe in the nerve- 
tubes. These minute tubes will, subsequently, be more circum- 
stantially described. The principal difference between the primitive 
tubes of the nerve-tubes and the tubes of the dotted substance is 
that, the latter have more distinct and deeper stained sheaths. Seeing 
how nerves are formed by the union of these tubes, it is, therefore, in 
my opinion, evident that they are primitive tubes with stouter sheaths 
than they have in the nerve-tubes. These, the sheaths, in the 
dotted substance, seem to be formed or, at all events, made stronger 
by the same neuroglia which also envelopes the nerve-tubes; this 
neuroglia does not seem, however, to be very distinctly distinguished 
from the spongioplasm, as we have, also, previously seen in the 
ganglion cells (cf. p. loo — 102). Inside these primitive tubes, I have 
been able to observe any structure, only the hyaline substance, 
hyaloplasm, above mentioned. The granules which have given the 
dotted substance its name, are, partly, thickenings in the sheaths of 
the tubes, especially along their concreting edges; to some extent 
they are extremely slender tubes traussected (vide sequel). 
The meshes which are somewhat larger than those small meshes 
in the dotted substance, are, I think, transsected small nerve-tubes 
consisting of a few primitive tubes only. 
We have thus, in the dotted substance in the ganglia of Ho- 
marus, a complicated plaiting or web of primitive tubes, and partly 
of nerve-tubes, of various sizes. On examination of longitudinal 
sections we wiU lind that, these tubes have in the dotted substance 
of the ventral ganglia, to a certain extent, a tendency to follow a 
ongitudinal course; this is especially the case in the parts where the 
nerve-tubes issuing from the longitudinal commissures are situated. 
To some extent, we also find bundles of nerve-tubes running trans- 
versally as commissures from one side of the central nerve-system 
to the other, or also running to the peripheral nerves. 
Smaller or larger distinctly defined masses, apparently consisting 
exclusively of primitive tubes, are mesially situated in most ganglia; 
they are, however, especially prominent in the first ventral ganglion 
and in the brain; fig. 61 represents, as before mentioned, a part of 
such a mass situated, mesially, in the first ventral (thoracic) ganglion. 
