— 199 — 
of the nerve-tubes. The spongioplasmic walls of the pri- 
mitive tubes are distinctly seen in the nerve-tubes. (From 
a preparation treated as above.) 
Plate III. 
The illustrations of this plate are drawn under the camera 
lucida, from the microscope directly upon the stone (except fig. 23). 
The preparations (exept fig. 23) are fixed in chromo-aceto-osmic acid, 
stained according to Heidenhain's hæmatoxyhn method (except fig. 24) 
and some of them afterwards with Delafield's hæmatoxylin. All the 
illustrations are tåken from ganglion cells of 
Ho manis vulg ar is. 
Fig. 23. (Magnified 620 diameters; Zeiss F, i. Camera lucida.) 
A & B Ganglion cells (from a ventral ganglion) isolated 
in acetic acid (i), glycerin (i), and aqua dest. (5), and 
stained with picro-carmine. a Space surrounding the 
central bundle of primitive tubes (b) of the process, and 
in which no structure is visible, n, n Neuroglia nuclei 
situated outside the sheath of the cell and the process. 
» 24. (Magnified 620 diameters; Zeiss F, i.) Part of a section 
through two ganglion cells (A & B) and the neuroglia (nu) 
situated between them. A & B Parts of the protoplasm 
of the two ganglion cells, in which a spongioplasmic re- 
ticulation is distinctly visible, cm, cm Neuroglia-sheaths 
of the cells. a Transsected, spongioplasmic fibres pene- 
trating, from the sheaths into the protoplasm of the 
ganglion cells. h Such a fibre seen in connection with 
the sheath. sp Similar fibre subdividing and forming a 
reticulation. nu Neuroglia. n Neuroglia-nuclei. 
» 25. (Magnified 350 diameters; Zeiss CC, 4.) Section through 
a large ganglion cell (of an abdominal ganglion) and the 
root of its process ; the lightly staining contents of which 
partly originates from bundles of primitive tubes, s, s Fi- 
bres penetrating from the neuoglia-sheath into the proto- 
plasm of the cell. a Similar fibres transsected. 
» 26. (Magnified 750 diameters; Zeiss F, 2.) Section through a 
ganglion cell and a part of its prosess, the contents of 
which arises equally from the whole protoplasm of the 
cell by a convergence af primitive tubes, nu Neuroglia, 
cm Sheath of a ganglion cell. 
