— 209 — 
Fig. 89. Phallusia venosa. (Magnified 750 diameters; Zeiss F, 2.) 
Nerve-tubes and ganglion cells (gc) from a brain, ma- 
cerated in weak solution of alcohol. a Nervous process 
from which side-branches are given off. h — e Nerve-tubes 
from which side-branches are given off. 
» 90. AmpMoxus lanceolatus. (Magnified 350 diameters; Zeiss 
CC, 4.) Transverse section of the spinal cord. gc, gd 
GangUon cells. pp Protoplasmic process. vnt Ven- 
tral colossal nerve-tube. Int Lateral colossal nerve- 
tubes. cg Central groove (or canal). / Fibres crossing 
the grove, nf Fibres issuing from the epithelial cells sur- 
rounding the central groove and penetrating to the sheath, 
enveloping the spinal cord. ns Similar, thick fibres, united 
to strong bundles, one on each side of ventral, colossal 
nerve-tube. p Pigment, nt Slender nervetubes running 
transversally in the white substance. (Fixed in chromo-acefo- 
osmic acid, stained according to Heidenhains hæmatoxy- 
lin method and afterwards with Delafields hæmatoxylin). 
» 91 . AmpJiioxiis lanceolatus. (Magnified 7 50 diameters ; Zeiss F, 2.) 
Transsected large nerve-tubes from the a transverse sec- 
tion of the spinal cord. (Preparation same as in fig. 90). 
» 92. Amphioxus lanceolatus. (Magnified 620 diameters; Zeiss 
F, I.) Ganglion cell (gc) from a transverse section of 
the spinal cord. pp Protoplasmic process penetrating to 
the sheath (a) enveloping the spinal cord. pp^ Protoplasmic 
process, which possibly crosses the central groove, and 
which in this section is transsected. cg Bottom of the 
central groove (or canal). c EpitheUum. ec Epithelial 
cell. p Pigment occurring at the bottom of the central 
groove. ns Fibres issuing from the epithelial cells and 
in which some pigment is deposited. (Fixed in osmic 
acid (i ^/y), stained with ammonia-carmine). 
Plate X. 
•' The illustrations of this plate are drawn under the camera lucida, 
from the microscope directly upon the stone. They are all tåken 
from sections of the spinal cord of 
Myxine glutinosa. 
I^ig- 93- (Magnified 132 diameters; Zeiss AA, 4.) Transverse 
section of the spinal cord. (To some extent composed 
Lfrom several sections of series of transverse sections, 
