352 Professor E. B. Poulton on colour-relation 



E. The three sirnilar htrvji', with hlacl- twif/s. — These also 

 were practical!}- unchanged and like D. One of these 

 was now the blackest larva, but the smallest in D was 

 almost exactly the same. It is possible that some very 

 slight etfeet was produced by these black twigs before 

 hybernation. 



F. One of the three lightest larrm unth lichen-covered sticks. 

 — The larva was quite unchanged. 



G. Two of the three lightest lanw irith black twigs. — No 

 eftiect had been produced by the black surroundings. The 

 bluish-grey larva remained very distinct. 



H. Two larva' with lichen-covered sticks. — The brownish 

 larva had died. The other still remained the darkest 

 individual of the lighter part of the group (F, G, H) as 

 it was when the arrangements for hybernation w^ere made. 



Comparing these two important groups I and II as a 

 whole, it was seen that the lightest larva of I (in A) was 

 almost precisely similar to the darkest of II (in E) : — in 

 fact they could not have been distinguished as regards the 

 size of the light patches. On the other hand, the larva in 

 I was healthy and of the average size, while that in II 

 was rather small. The smallest in D was not considered in 

 this comparison, as it had grown but little and was a stage 

 behind the others. Its light patches, although very dull 

 and grey, were almost exactly the same size as those of the 

 darkest larva in D. The remaining nine larvse in II were 

 al] large and healthy, and much lighter than the lightest 

 larva in I. 



III. THE QUERCIFOLIA LAEV.E WITH BROWN BRAMBLE- 

 STEMS BEFORE HYBERNATION. 



Compai'ing these as a whole with sets I and II it was 

 obvious that the lightest of them was distinctly dai'ker 

 than the darkest of the group just described (II) and exposed 

 to lichen before hybernation. The larva? were perhaps as 

 dark as those in group I, exposed to Turkish oak before 

 hybernation, but they were not so black, and, except in two 

 larvje, the light markings were less white, being greyish 

 and clouded over. 



I. TJic fonr unifoo'ni dark larvm with lichen-covered sticks. 

 — Two larva? were verV dark with a dull blackish oround- 



