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on the fact of the scales containing a particular pigment or 
colouring matter, while other members thought it might pro- 
ceed solely from light reflected from the irregular surfaces of 
the scales. 
On examining lately, by transmitted light, the wings on 
one of the clear- winged moths — Sesia Tipuliformis — I 
found on the transparent portion of the wing, and in addition 
to the markings on the wing, certain other scales of battledore 
form and perfectly transparent. 
An examination with a higher power showed these scales 
to be highly striate, and therefore in the most proper con- 
dition for producing, according to the advocates of the theory 
I oppose, metallic lustre and metallic markings ; and that 
they are in a condition to produce these effects, were the 
theory correct, is further shown on examination by reflected 
light — when, as might be expected from the markings, the 
scales are most beautifully opalescent, but wanting internal 
pigment give out no metallic markings on the Aving, and 
a strong proof is, therefore, given in favour of the theory 
broached by me. 
Ordinary Meeting, October 19th, 1863. 
Prof. W. C. Williamson, F.P.S., in the Chair. 
The following paper cc On Transparent Injections,” by 
Messrs. J. G. Dale, F.C.S., and Thos. Davies, AA'as read 
by the Secretary. 
After enumerating the various de’siderata of a transparent 
injecting fluid, it Avas observed that soluble colouring matters 
failed to fulfil them, owing to the action ofendosmos, causing 
them merely to dye the tissue sought to be injected. This 
defect is shown to be remedied by the use of insoluble 
colouring matters in an exceedingly fine state of subdivision, 
Avhich can only be prepared by precipitation under constant 
