LEPIDOPTEROUS PUP^E AND THEIR SURROUNDING SURFACES. 
399 
4 pupae in Series 2 was figured, and is shown in fig. 13, X 2, Plate 26, but there was 
not much difference between them. 
The pupae in black surroundings were immensely different, the ground-colour being 
much darker, and the only golden appearance being on the tips of the sub-dorsal 
tubercle, spreading a very little on to the sides of the latter, while none reached the 
general surface of the pupa. In Series 2 one pupa was much darker than the other, 
and in it most of the tubercles have no golden colour on their apices, which are 
merely of a lighter colour than the rest of the tubercle. This pupa was figured, and 
is shown in fig. 12, X 2, Plate 26. 
The pupae in the clear glass cylinder were intermediate between the two above- 
described varieties, but were nearer to the golden ones. 
These results are extremely interesting in their specific peculiarities no less than 
in their harmony with the effects wrought upon the pupae of V urticce. As far as the 
experiments went there was nothing at all comparable to the amount of golden colour 
common upon the varieties of V. urticce represented by (4) and (5), although the 
difference between the two forms, caused by the gilt and black surroundings 
respectively, was exceedingly marked, and the gilt appearance, though limited in 
amount, was perhaps more brilliantly metallic than in V. urticce. The length of 
Stage III. seems to be about the same as in the latter species. 
The Biological Value of the Gilded Appearance in Pupce. 
It has been long observed by many entomologists that the excessively gilded 
pupae which are sometimes found in nature almost invariably contain the parasitic 
larvae of the Ichneumonidae, although Mr. T. W. Wood has proved that this is not 
necessarily the case. I need hardly say that my own brilliantly golden pupae, 
produced by experiment, were entirely healthy, and I had no instance of the presence 
of parasites in any of them. Large numbers of them were allowed to develope 
into Butterflies, and these finally emerged in a perfectly normal manner. However, 
three pupae of Vanessa urticce, found wild upon the food-plant during the past 
season (1886), were more golden than is usual in nature, and all three contained 
parasites. The contrast between the golden pupae produced by gilded surroundings 
and by disease certainly indicates that the former is the normal association, the latter 
being probably merely incidental. It is probable that the diseased state of the larva 
in some way prevents the formation of pigment in the pupa, and then the golden 
appearance is formed which is always normally associated with the absence of pigment. 
It is quite clear that these interesting results of abnormality offer us no explanation 
whatever of the normal use of the gilded appearance. The first suggestion was made 
by Mr. T. W. Wood in the previously quoted paper—that a gilded pupa does not 
resemble any object which is of interest to the enemies of its class; but, looking more 
like “ a piece of gold or brass than anything else,” is likely to be passed unnoticed. 
