404 Mr. 0. H. Latter on the secretion of 
ment progresses, they become less granular and more 
transparent, while the colour changes to a greenish- 
black. The pigment, however, seems to cling to the 
walls, leaving the central portions of the fluid almost 
colourless. 
It appears to me that we have here a fairly complete 
explanation of the somewhat astonishing behaviour of 
the imago in discharging an alkaline fluid. The digestive 
fluids of the larva are alkahne, their work ceases with 
the end of larval hfe, the walls of the mesenteron retain 
their power, and the alkaline liquid produced is retained 
and perhaps strengthened by concentration while being 
stored in the dwindled mesenteron itself and in the 
special receptacle constituted by the dorsal diverti- 
culum. 
I have not been able to analyse the alkahne liquid in 
the larval mesenteron in consequence of lack of material, 
so that the proof of the identity of the two fluids is not 
complete, though the balance of probability is in favour 
of their being one and the same. 
There can be little doubt that the secretion is 
expelled along the oesophagus by means of the pressure 
which is brought to bear upon the mesenteron and its 
diverticulum, by the violent muscular contractions of 
the bodywall at the time when the imago splits open 
and struggles out of the pupa case. 
(vi.) Alhaline secretions discharged by other species. 
I have proved, by the employment of artificial cocoons 
of red litmus paper, that the following species eSect a 
softening of their hard cocoons by discharge of alkaline 
liquid from the mouth: — Dicranura bifida (abundant), 
D. furcula (abundant), Bombyx callunse (abundant), 
B, lanestris (slight), Saturnia carpini (abundant), 
Limacodes testudo (slight), and Halias prasinana 
(moderate quantity). I have not been able to procure 
sufficient material for analysis from any of these. 
Pupae of the following were also experimented with, 
but no results obtained — Endromis versicolor, Pygsera 
bucephala, Mamestra brassicx, and Cucullia absynthii. 
As in jD. vinula, so too in most of the others which 
produce alkaline liquid, there are also mechanical con- 
