Notes on Myriapoda. 17 
L cation. 
Our first enquiry must be: What is the exact seat of 
luminosity in G. carpophagus ? 
In some of our earlier experiments we found that an 
excretion on to the ventral surface of the body caused the 
light in this species, and the examination of specimens 
ventrally under the microscope showed that opaque rounded 
masses of material were often present under the pore-field 
and under the surfaces of the plates known as 28 and 2+¥ 
(fig. 2). We know now that these white rounded masses are 
groups of pyriform and probably unicellular glands intimately 
associated with the production of light (PI. I. fig. 9 and PI. IL. 
fig.11). When we stimulated specimens provided with these 
elands in a holder under the microscope in the dark, so that 
we could observe the production of light by the animal, we 
found that soon after the application of the stimulus there 
was a sudden rush of light filling in tie grooves behind the 
sternite and around the outer edges of the plates 2 8 and 2 y, 
and also filling in the grooves between these plates and the 
sternite itself (Pl. I. fig. 10). When the centipedes were ex- 
amined subsequently in direct light, it was found that the 
** white glands” of the stimulated segments had disappeared 
either entirely or almost entirely (PI. II. figs. 11 & 12). 
Thus, luminosity in Geophilus carpophagus és entirely ventral 
in incidence and is accompanied by the discharge of the 
“white glands.” 
The luminous material in G. carpophagus is a viscous 
fluid, practically colourless, with a characteristic fruity 
odour not unlike that of some decaying flowers, drying 
rapidly in air, and strongly acid in its reaction. 
By means of a partial illumination (PI. I. fig. 8), instead of 
working absolutely in the dark, we were able to observe the 
incidence of luminosity with greater accuracy and also to 
watch the behaviour of the “ white glands” upon stimula- 
tion. The amount of illumination employed in such experi- 
ments should be just sufficient to make the outlines of the 
“white glands ” distinguishable under the microscope. We 
found that immediately upon a muscular contraction of the 
body and the discharge of the ‘‘ white glands” to the ex- 
terior luminosity is produced, and in one case the expulsion 
of their contents was sufficiently slow to admit of more 
detailed observation. On electrical stimulation the opague 
patches (contents of the ‘“‘ white glands ”’) under the posterior 
part of the sternite were seen to move instantaneously 
Ann. & Mag. N. Hist. Ser. 9. Vol. v. 2 
