on the colouring of Pieris napi, ce. 59 
64° corresponding with such temperatures as may be met with in 
English summers, do not greatly differ inter se, but Class 1 at 80° 
to 90° differs appreciably from them. 
Class 1, compared with Classes 2, 3, and 4. On the wpper 
surface the black is not really black, but slightly suffused with 
golden brown, so as to give it a rusty look, and the scarlet bands 
are broad. At the three lower temperatures the black is intense, 
the scarlet band narrower, with a greater tendency to be broken 
up into parts on the fore wings and to be invaded by black scales at 
the anal angle in the hind wings; all the colours seem more in- 
tense, the intensity, I think, slightly increasing as between the 
3 classes with the lowering of the temperature, and there is cer- 
tainly with this lowering an increased development of the lavender- 
gray submarginal broken band. On the wnder surface of the fore 
wings of 2 out of the 12 at 90° a new small scarlet spot appears 
between the scarlet band andthe inner edge. On the under surface 
of the hind wings of those at the three lower temperatures there 
is an even stronger intensification of colouring than on the upper 
surface, and especially of the dark colouring. The ground colour 
of the hind wings is decidedly much darker than in those at the 
higher temperature. On the other hand, the light parts are de- 
cidedly lighter and more strongly marked in those at the lower 
temperature. The chief of these light parts are—(1) a conspicuous 
cream coloured spot, something like a figure of 8 with the upper 
loop much the larger; this spot becomes more dense and con- 
spicuous, and the loops have a tendency to be filled up and to 
spread along the costa, so as to give the spot a triangular form. 
(2) a light ochreous cloud near the middle of the hind margin. 
This becomes lighter and more strongly marked, and light cloudy 
markings begin also to appear near the centre of the hind wings. 
These effects on the under surface of the hind wings mostly 
increase with the progressive lowering of the temperature. 
In Class 5 there is no great difference on the upper surface, the 
scarlet being, however, a little deeper in hue, but on the under side 
of the hind wings the effects of the low temperature are visibly 
enhanced—the creamy spot becoming denser and increasing in its 
tendeney to spread along the costa, and the light cloudings be- 
coming more marked and increasing in area, and even appearing 
in additional places. A few of these individuals show slight indi- 
cations of suffering from the temperature. 
Class 6. A sixth lot was kept wholly in the refrigerator at about 
45° (corresponding with the latter part of an English November) 
for from 82 to 47 days, and then brought into various tempera” 
tures ranging from 90°, at which they emerged in 6 days more to 
