— 103 — 
centric striation. Some of the primitive tubes we can in many pre- 
parations even trace, for some distance, in their course through the 
cell-protoplasm, of which they are not, as we have previously seen 
(cmfr. reticulation described p. lOi), the only constituent, but of 
which they are, however, a principal part. These primitive tubes 
have the same structure and diameter as those we have described 
in the nerve-tubes; they consist of hyaline contents, hyaloplasm, 
enveloped in sheaths of spongioplasm, which has the same staining 
and appearance, and is evidently the same substance, as that pre- 
viously described (vide p. loi), as forming the reticulation in the 
cell-protoplasm. In hg. 27 and 28 it is very distinctly seen that 
these spongioplasmic sheaths ot the primitive tubes are intimately 
connected with the peculiar peripherically situated fibres (fig. 27, b ; 
fig. 28, 5) issuing from the surrounding neuroglia-membrane. 
In a great many ganglion cells these primitive tubes have not, 
however, such an uniform extension through the protoplasm as 
illustrated in fig. 26. In the large cells they are generally united 
to bundles, distinctly distinguished from the rest of the protoplasm. 
In successfully stained sections,^) where they are transversally trans- 
sected, they are distinctly visible as larger or smaller light areas 
situated in the deeply stained protoplasm. Very often, when the 
bundles of primitive tubes circulating in the cell-protoplasm are 
numerous and small, we get sections having the appearance illustra- 
ted in fig. 25 and 27. 
In ganglion cells containing such bundles of primitive tubes circulat- 
ing in the protoplasm, the nervous process arises in such manner that 
the bundles unite to form the process, as illustrated in fig. 27 and 25. 
This union takes place generally within the cell-protoplasm, and the 
contents of the nervous process has then, for some distance, an un- 
divided course through the cell-protoplasm, and can be traced as a 
large light area through a series of transverse sections (cmfr. fig. 
28 and 29). It is surrounded by thicker or thinner deeply stained 
.fibres (fig. 28, s and h; fig. 29, s and 5') of the same substance as forms 
the reticulation of the protoplasm (cmfr. p. loi). Some of these 
^) That it really is primitive tubes, with slightly stained hyahne contents, and 
not »fibrillæ« which circulate in the protoplasm of the ganglion cells, is easily 
seen in prep arations deeply stained by hæmatoxylin (e. g. fig. 37) ; they are distinctly 
visible as light concentric lines where they are longitudinally transsected (cmfr. 
also fig. 38). 
^) The fixing method and staining described p. 76 and p. 85 can especially 
be recommended for this purpose. 
