on the colouring of Pieris napi, Lc. 61 
the scarlet band on the upper wings clouded with a whitish yellow 
colour, and that this is the result of temperature is shown by the 
other of the two, which exhibits a trace of the same colouring. 
There is also a tendency to yellowness of the scarlet band on the 
hind wings in some of those which are more or less crippled. 
The results with V. atalanta may be summed up as 
follows :— 
I. At 90°, pupal period 6 days (Fig. 3). Upper 
surface.—The black is rusty, the scarlet is of wide area 
and bright. Under surface.—The ground colour of the 
hind wings is brown, not dark brown, the light parts not 
very light. In two a new scarlet spot appears between 
the scarlet band on the fore wings and the inner edge. 
II. At 64° to 51°, period 18 to 50 days (Fig. 4). 
Upper surface.—The black is intense, the scarlet rather 
deeper in colour and narrowed. Under surface. Ground 
colour of hind wings dark brown, light parts lighter. 
IIT. At 45°, period 47 to 32 days, and then at various 
temperatures from 90° to an average of 55°, emerging 
in from 19 to 34 days more (Figs. 5 and 5a.) Upper 
surface.—F urther invasion of scarlet by black, scarlet band 
further narrowed and broken up, and of a hue approach- 
ing carmine; spread of white and lavender scales over 
black parts, edges of spots diffused ; minute blue or lilac 
spots on orange marginal band of hind wings increased 
in number. Under surface.—Great increase in lightness 
and area of light parts; diffusion of edges of spots 
and of some markings, and appearance of some new 
markings. 
The results obtained by extreme and protracted cold 
i.e., 45°), though probably such as would rarely be met 
with in nature, seem to me exceedingly interesting — 
first, as proving by this extreme case that the less marked 
intermediate results are caused by temperature; and 
secondly, because, owing to the great change in marking 
and colouring which they exhibit, especially on the 
under side of the hind wings, they may, it seems to me, 
possibly throw some light on the evolution of the mark- 
ings in the Vanessas. This difference of appearance in 
these extreme cases is so great that I think if some of 
the insects could be seen in the resting position, 7.e., 
showing only the under side of the hind wings and the 
