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XIV. Further Notes on the Secretion of Potassium 
Hydroxide hy Dicranura vinula (imago), and similar 
Phenomena in other Lepidoptera. By Oswald H. 
Latter, M.A., Assistant Master at Charterhouse, 
formerly Tutor of Keble College. 
[Read March 20th, 1895.] 
Plates VIII. and IX. 
In my previous communication on this subject (Trans. 
Bnt. Soc. Lond., 1892, Part IV., pp. 287-292) a few 
points were left in doubt. Some of these I have been 
able to clear up, and at the same time I have proved 
that an alkaline fluid is produced from the mouth by 
imagines of other species at the time of their emergence 
from the cocoon. By the kind aid of my former 
colleague, the late Eev. S. D. Titmas, I have been able 
to make a quantitative analysis of the secretion produced 
by D. vinula. 
I will deal with this species first and then proceed to 
the others, which I have not been able to investigate 
so fully. 
(i.) The cocoon of D. vinula. 
I am disposed to think that the difficulty experienced 
by the moth in escaping from the cocoon has been 
rather over-estimated. If a cocoon is examined from 
the innerside, while held towards the light, it will at 
once be seen that the walls are not of uniform thickness, 
but that thinner patches occur here and there. I 
examined over a hundred cocoons in this way, and 
invariably found one of these thinner areas at the 
anterior end opposite the head of the pupa. Such an 
arrangement obviously must lessen the labour of the 
imago at emergence. 
(ii.) The removal of the pupal shield by the imago. 
In my former paper I was unable to speak definitely 
of the manner in which the imago frees its head from 
trans, ent. soc. LOND. 1895. — part in. (sept.) 
