778 SUMMARY OF CURRENT RESEARCHES RELATING TO 
granular mass, a bundle of threads, or a thick, striated, cuticula-like 
mass. The constriction seen in some pleuropodia is probably homolo- 
gous with one of the constrictions which separate the thoracic and 
maxillary appendages into segments. In some cases, at least, no 
chitinous cuticle is formed over the surface of the pleuropodial cells. 
These organs attain their greatest development during the revolution of 
the embryo, but soon after the yolk has been enclosed by the body- walls, 
and the heart has formed, they begin to degenerate. This degeneration 
does not always result in a reabsorption into the body of the embryo, 
but in a falling asunder of its large cells, and their subsequent dissolution 
outside the body of the Insect. 
With regard to the function of these organs, it has been suggested 
that they are gills, sense-organs, or glands ; the author, for reasons 
which he gives, is inclined to accept the third of these suggestions. 
Scale-Pigments of Lepidoptera.* — Dr. F. Urech has investigated 
the various kinds of pigments found in the scales of some Lepidoptera, 
and arranges them under five heads ; (i.) Scales which only contain 
chemical colouring matter, and can show no interference colours ; (ii.) 
Those which contain chemical colouring matters, but are also able to 
show interference colours, as the scales of species of Vanessa; (iii.) 
Scales which only show interference colours on the wings, though they 
contain chemical colouring matters soluble in water, as species of 
Lycsena ; (iv.) Scales whose coloration is due to the underlying layer, 
as the blue and violet scales of species of Vanessa; and (v.) Variously 
coloured overlying scales often show mixed colours as in Papilio 
Machaon. 
In the scales which show interference colours, two kinds may be 
distinguished ; the colours are only visible when the scales are removed 
from the wing, and brought into definite relations to the rays of light ; 
or the colours are visible on the wing if the scales are removed from the 
opposite side, and the wing held in certain positions. The second group 
of colours are visible in reflected light when the scales are on the wing, 
but they generally vary in two colours only, and that according to the 
position of the reflected light (e. g. Apatura Iris, and species of 
Lycsena.) 
Green Pigment in Wings of Chrysalids of Pieris brassicae.j — 
Dr. F. Urech finds this when the unexpanded wings have their scales 
carefully removed. If the young wing is placed in water the fluid is 
coloured ; after evaporation there remains a deep-green membranous 
mass. This, on being again bathed in water, is not wholly dissolved, 
a pale portion remaining. Thus it seems that in the first solution some 
substance associated with the pigment is dissolved, which after drying 
becomes insoluble. It may be a substance which gives rise to the 
pigment, or it may be merely its bearer. The green pigment is not 
chlorophyll ; nor is it identical with the scale-pigments, though perhaps 
representing a preparatory stage ; nor is it the pigment of the blood. 
Pupine4 — Dr. A. H. Griffiths gives the name of pupine to a new 
substance which he has extracted from the skin of the pupas of three 
* Zool. Anzeig., xv. (1892) pp. 305-6. f Zool. Anzeig., xv. (1892) pp. 281-3. 
X Comptes Rendus, cxv. (1892) pp. 320-1. 
