oF Dr. & the Rev. 8. Graham Brade-Biks— 
as the film dries. The experimental estimation of brightness 
has already been explained. 
We bave made no examination of the phosphorescence of 
these animals with the spectroscope. 
The Chemical Considerations. 
When we come to consider the chemical possibilities of 
the question, our path is fraught with many difficulties ; one 
of the most important of these is the drawback due to the 
small amount of material available for chemical analysis. 
At the outset it is necessary to consider as carefully as 
possible the substances with which we are dealing, and so in 
the first place let us examine the products of the glands of 
the sternite and its associated sclerites. 
We have already described the discharge of the contents 
of the ‘ white glands ” into the grooves behind the sternite 
in the case of the electrical stimulation of G. carpophagus. 
Ii one instance a specimen of this species was electrically 
stimulated in a partial illumination under the microscope. 
The luminescence of the centipede was not very marked, but 
there was noticed flowing over the sternal plate and especially 
over its posterior region a quantity of a viscous excretion, 
with a suggestion that it arose from the pore-field and from 
thence spread over the sternite. There can be little or no 
doubt that such an excretion contains mucin. 
We experimented with a specimen of Geophilus insculptus 
taken in a Darwen garden 27. vii. 1919. No “ white glands ” 
were observed and the animal was not luminous on electrical 
stimulation, but mucin was seen to flow through the pore- 
field of the sternite and form a film by capillary attraction 
between the sternal plate and the glass of the holder. The 
mucin obtained was odourless. In a similar instance of a 
specimen of G. insculptus collected in the same garden the 
next day, the film of mucin obtained was found upon drying 
to contain crystallme needles when examined under the 
microscope, a fact already referred to in dealing with 
crystallization earlier in the present study. 
It must be added that in the case of Stigmatogaster sub- 
terraneus (Shaw) * non-luminous mucin has been seen to 
flood the grooves around the sternite and the episternal 
plates, 28 and 2y¥, on the electrical stimulation of the 
animal. 
y] 
* Often attributed to Leach; syn. 1789, Scolopendra subterranea 
Shaw, Trans. Linn. Soc. ii. p. 7. 
