40 
whether it may not be that the best “protections” are not found out 
at all. Those known, however, are wonderful, and wide enough for 
our admiration and good testimony to the importance of “ under¬ 
sides.” 
Contrast development of uppenid.es. — This may seem a mere one¬ 
sided panegyric on the underside unduly separated from its association 
with the upperside, but a growing appreciation has rendered one more 
than suspicious that the main use of undersides — protection — may 
partly owe its capabilities or success to the uppersides having developed 
on lines of contrast, in many cases. This is strongly suggested by 
such forms as Thet-la rubi, Lycaena bellaryus and allies, P. ulysses, 
the Delias and other Pierid groups. The bright colour having its 
display on the upperside, but often the upperside having a duller 
contrasting colour, are opposing arrangements which strongly emphasize 
this. If the underside has been determined by adaptation to dull, 
or bright coloured surroundings respectively, or with bright warning 
colours, the chances of escape may easily be enhanced by a contrast 
forming on the upperside in two w r ays at least. 
(1) In elusion on settliny. — Thus the blue L. bellaryus J , by a 
sudden closing of the wings, becomes not recognisable as the same 
insect, if as an insect at all, and therefore not liable to be identified as 
the object of the chase — without a process of education, which may 
never be completed in the foes. The greater the contrast, the less is 
there any preparation to foreshadow the unexpected and detract from 
the “ quick change” process. The protective undersides, if this is 
true, have an enhanced value for resting insects, through the develop¬ 
ment of a brilliant upperside. And the same result is obtained by the 
opposite process of a nearly black upperside contrasting with the pro¬ 
tective bright underside of T. rubi. 
(2) Co-operation of upperside and underside . — A process of true co¬ 
operation is suggested. Such is shown by such a butterfly as Delias 
nysa with a black underside and white upperside, which, when flying, 
represents a third brilliant silvery butterfly — a “fusion” effect. 
These contrast butterflies, bellaryus , rubi, etc., are much less con¬ 
spicuous when flying, and much more difficult, on account of varia¬ 
tions in appearance, to follow in their flight than the others, which 
one may call repetition-surface butterflies, e.y., C. rhamni, English 
Pierids, E. cardanrines 3 , P. machaon, etc. The comparative ease 
with which the sight can follow the latter is familiar to all. Even an 
almost black butterfly, with repetition-surfaces, in flying suddenly into 
shade, is much more easy “ to keep one’s eye on ” (let alone a Pierid 
or other repetition-surface) than is a contrast-surface butterfly — 
T. rubi, D. niyridius, etc. 
In this co-operation process many species may more or less be 
included, perhaps, but one tends to overlook the details of one’s 
experience often in one’s anxiety, and success or disappointment in 
attempting to avoid co-operating oneself in the insect’s escape. But 
we can easily recall one instance in Ino statices, and recollect how 
comparatively inconspicuous it is rendered in flight, by the co-operation 
of the gray hindwings and duller underside, than when we depended 
for recognition solely on its metallic upper wings’ colour undiluted, 
i.e., “ unfused.” 
xix. 
