J 
in eye-units 
Notes on Myriapoda. 21 
A Comparison. 
We may add here that crystals have been observed in the 
dried films of excretion obtained in our holder, not only from 
the ventral surface of luminous specimens of G. carpophagus, 
but also in one case from a non-luminous specimen of 
Geuphilus insculptus, Attems, taken in a Darwen garden 
28. vil. 1919. 
The Incidence and Decline of Light Production. 
Quite roughly we have prepared a number of curves to 
show the incidence and decline of luminosity which follows 
Fig. 14. 
1004 
90 
80 
70 
10 20 30 40 50.60 70 80 90 100 0 12Q 13Q 146 150 160 170 180 130 
7ime fn seconds — 
Curve to show incidence and decline of luminosity in Geophilus carpo- 
phagus. Description in the text. The data employed are those of 
Experiment 2 (see Table). 8S. G. B.-B. del. 
the electrical stimulation of a specimen of Geophilus carpo- 
phagus. Although the curves plotted are only roughly 
estimated, it seems worth while to give the figures of three 
experiments carried out in our own laboratory and to accom- 
pany them by a drawing (fig. 14) of one curve which serves 
as a type. Here it will be noticed that there is a short 
space of time between the sudden shock of electrical stimu- 
lation, which is only momentarily applied, and the incidence 
of light-production. The light is brightest when it is first 
observed, and it fades suddenly at first and more slowly later 
