326 Mr. 'Poulton's further experiments upon 



brownish shade or " bloom," either or both of which are 

 usually found when the green surroundings are contri- 

 buted by hawthorn. It would also be interesting to test 

 the effect of dark lichen-covered twigs on this very sensi- 

 tive species. 



While larva-beating during the past autumn (1892), I 

 have noted the colours of the larvte of this species beaten 

 from various bushes of hawthorn and blackthorn, and I 

 always found a most marked correspondence between 

 the appearance of the larva and the particular bush on 

 which it had lived. The bushes, even when belonging 

 to the same species, differ greatly in the darkness of 

 their twigs, and the amount of bloom-like superficial 

 colouring. These individual differences were faithfully 

 reproduced, showing the efficiency of the power of colour- 

 relation to surroundings in promoting concealment under 

 normal conditions. 



Some of the cocoons produced in these experiments 

 are described in Proc. Ent. Soc. Lond., 1888, p. xxviii, as 

 illustrations of the power of individual colour adaptation, 

 being brown when spun upon green paper and green 

 leaves, but white when spun upon white muslin. I 

 should not now advance these cocoons as examples of 

 the power until after renewed experiments have been 

 made, guarding against the sources of error pointed out 

 by Mr. Bateson. 



17. Experiments in 1886, 1889, and 1892 upon 

 Amphidasis betularia. 



1886. 



A single captured female laid the eggs which produced 

 the larvsB described in the tables below. 



When examined and compared Aug. 17th or 18th the 

 sizes of the larvaB were found to vary very greatly, but 

 none had entered the last stage. The following letters 

 were therefore used to express the sizes : — 



A. — Changing last skin. 



B. — Large in last stage but one ; over 300 mm. long when extended 



at rest. 

 C. — Medium size in last stage but one ; over 24-0 mm. long when 



extended at rest. 

 D. — Very small in last stage but one, or changing last skin but one. 

 E. — Earlier stages. 



{See Table, jntges 328, 329.) 



