— 121 — 
for some distance, concentrically, round the nucleus, giving the 
ganglion cells a concentrically striated appearance. 
In some ganglion cells, especially those of Hom ams and Neph rops, 
primitive tubes are partly united in bundles, or to smaller or larger 
masses situated in the protoplasm, and which are distinctly lighter 
staining than the rest of the protoplasm, in which, however, also, 
plenty of primitive tubes occur (hg. 38). 
In a great many, or possibly in all, ganglion cells a spongioplas- 
mic reUculation is present, extending from the enclosing neuroglia- 
membrane into the protoplasm, between the primitive tubes, and 
intimately connected with the spongioplasmic sheaths of the latter. 
This reticulation is very prominent, especially in the ganglion cells, 
of Homarus and Nephrops, where thick spongioplasmic fibres af a 
peculiar appearance, and connected with the reticulation often occur 
in the peripheral layers of the protoplasm, penetrating from the 
neuroglia-membrane into the protoplasm (fig. 24). 
Besides this reticulation, there is, probably, also a special, parti}' 
fatty (myeloid.f^) substance present in all ganglion cells of inverte- 
brated bilaterates, which substance does not generally occur in the 
nerve-tubes. This substance possibly occurs to some extent, in 
connection with the spongioplasmic reticulation, and extends between 
the primitive tubes of the protoplasm, giving the latter, in preparattons, 
the deep staining which is generally prominently different from the 
staining of the contents of the nervous processes and nerve-tubes 
where primitive tubes only occur. 
Whether it is the same substance which, in the ganglion cells 
of a great many animals (cf Polychæta, Mollusca etc), is connected 
with a pigment (hæmoglobin .r^) and gives the nervous S3^stem its 
special colour, I am not in a position to decide, although I think it 
not improbable. 
3) The processes of the gangUon cells are of two kinds; viz. 
nervous processes and protoplasmic processes. 
Of oiervoiis processes each ganglion cell in the central nervous 
system has ahvays one and never more. The nervous processes are 
generally directed, centrally, towards the dotted substance. 
When the ganglion cells are multipolar (the unipolar cell is, 
however, the most common type in invertebrated bilaterates) the 
other processes are protoplasmic ones, and they are generally short 
and directed peripherically, they having a nutritive function and 
being united with the neuroglia. As regards structure and appear- 
ance, they are quite similar to the protoplasm of ganglion cells. 
