316 MR. E. B. POULTON OX THE COLOUR-RELATION BETWEEN EXPOSED 
“ On a white surface pupae of Eronia cleodora became so pale-coloured as to be 
almost translucent, the marks on the ventral aspect of the abdomen being almost 
obliterated, and the bright yellow-green colour usually predominant almost invisible.” 
Mr. Trimen confirmed Mrs. Barber’s observations upon P. nireus in some experi¬ 
ments conducted upon Papilio demoleus, which is common at Cape Town. These 
results have not been published, but Mr. Trimen has kindly sent me an account of 
them in a letter. He says, “ I left my Demoleus larvae full liberty, within the range of 
their breeding-cage, to attach themselves to any of the bands of colour with which the 
sides of the cage were provided. I had noticed in nature that the pupae attached to 
the green upper twigs of the food-plants among the leaves were always more or less 
green or greenish, while those on the more brownish or greyish stems were coloured 
like the latter. Though more of these larvae suspended themselves to the food-plant, 
the remainder showed no apparent choice among the colours, but attached themselves 
indiscriminately all about. The colours which seemed certainly to directly affect those 
of the pupae were (irrespective of black, which made them a little darker) green, 
yellow, and reddish-brown, these tints being more or less reproduced. Bright red 
and bright blue had no apparent effect. I did not repeat the experiment, finding 
this one so confirmatory of Mrs. Barber’s observations on another species of the 
same genus.” 
Finally, Professor Meldola, knowing that I was looking out for any notices of the 
literature of the subject, kindly sent me the following translation of an important note 
in ‘ Kosmos,’ by Fritz Muller, showing that the pupae of Papilio polydamus, although 
dimorphic—green and brown—like our own P. machaon, are, nevertheless, like it, not 
susceptible to the influence of surrounding colours. 
“According to the observations and experiments of Wood on P. rapes, and 
of Mrs. Barber on P. nireus, the colour of the pupae in these Butterflies is deter¬ 
mined by the colour of the object on which they pupate. Nevertheless, this does not 
hold good for all Butterflies of which the pupae are differently coloured; it is not the 
case, e.g., in P. polydamus. The pupae of this Butterfly, which in former years I saw 
in large numbers, are either green or brown, and I have never found intermediate 
colours. The ground colour of the larva which lives on Aristolochia varies within 
wide limits ; pure black and bright yellowish or reddish-brown caterpillars are seldom 
found, but all possible stages between these extreme colours are common. The colour 
of the larva, however, has nothing to do with that of the pupa, and from both kinds 
of pupae similarly coloured Butterflies are developed, both rnades and females. 
The Butterfly always lays several (4 to 6) eggs close together ; till the second 
moult, the young larvae also keep together; they eat the same leaf and sit close 
together when at rest (like the social larvae of P. evander, till they pupate). Such a 
society of young larvae that I observed from the eggs in my garden I recently 
transferred to a large glass case before they distributed themselves over different 
leaves, and from this, as they prepared for pupation (i.e., when their excrement, 
