— 197 — 
A&B Large nerve-tubes with striated axes (c, (^). a, a Neu- 
roglia layers between the nerve-tubes. & Small nerve- 
tube with a visible longitudinal striation. e, e Small nerve- 
tubes without visible striation. 
Fig. 13. Homarus vulgaris. (Magnified 950 diameters ; Zeiss. Hom. 
im. V18» I- Cam. lue.) Large nerve-tubes {a, a) from a 
peripheral, abdominal nerve, and seen in the nerve in the 
live state; no striation is visible, h Sheaths of the nerve- 
tubes. c, c, Apparent septa, optic illusions produced 
by a slight bending of the nerve-tubes and their sheaths. 
h Neuroglia-nucleus situated inside the sheath of the 
one nerve-tube. 
» 14. Nereis virens. (Magnified 190 diameters; Zeiss. CC, 2. 
Cam. lue. direct upon the stone.) Transverse section of 
the ventral nerve-cord. cu External cuticulum. ep Thick 
ectodermal epithelium, outside the ventral nerve-cord. 
Tc Nuclei of the high cylindrical cells of this ectoderm. 
epx The common ectoderm of the body. h> The nuclei 
of this ectoderm. n, sJi »Connective« or neuroglia tissue 
surrounding and enveloping the ventral nerve-cord. å" 
Nuclei of this tissue. Similar nuclei, situated more 
ventrally, towards the ectodermal epithelium, from the 
nuclei of which they are not easily distinguished. 
gc & gc' Ganglion cells. m, m Membrane separating the 
ectoderm and the ventral nerve-cord from the inner layers 
of the body. (From a preparation fixed in Flemming's 
chromo-aceto-osmic acid and stained with Delafield's 
hæmatoxylin.) 
7> 15. Homarus vulgaris. (Magnified 620 diameters; Zeiss F, i. 
Cam. lue.) Isolated, largish nerve-tubes from an oeso- 
phageal commissure, macerated in acetic acid (i), glyce- 
rin (i) and aqua dest. (5). 
» 16. 'Homarus vulgaris. (Magnified 620 diameters ; Zeiss F, i. 
Cam. lue.) Isolated smallish nerve-tubes from an oeso- 
phageal commissure, macerated in the same way as in 
fig. 15. 
» 17. Patella vulgata. (Magnified 620 diameters; Zeiss F, i. 
Cam. lue. direct in the stone.) Nerve-tubes from a pedal 
nerve-cord and a peripheral nerve, macerated as above. 
» 18. Patella vulgata, (Magnified 620 diameters; Zeiss F, i. 
Cam. lue.) Nerve-tubes macerated as above, stained with 
picro-carmine. 
