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VI, Lxperiments in 1909 and 1910 upon the colour- 
relation between lepidopterous larvae and pupae 
and their surroundings. By ELIZABETH BRIDGES. 
Communicated by Prof. E. B. Poutron, D.Sc, 
M.A.,. F-R.S., ete 
[Read November 2nd, 1910.] 
I. Experiments on the larva of Uropteryx sambucaria. 
Il. Transference experiments on the same. 
III. Experiments on the pupa of the same. 
IV. Note on some experiments on the larva of Odon- 
topera bidentata. 
V. Notes on the apparatus used. 
I. Kuperiments on the larva of U. sambucaria, 
The following experiments were undertaken with the 
object of finding out to what extent the close resemblance 
of certain lepidopterous larvae to their surroundings is 
due to the adaptive power of the individual. — Prof. 
Poulton * has already shown that several species (notably 
fe. crataegata, A. betularia, O. lidentata, G. quercifolia, 
etc.) do possess in a remarkable degree the power of 
assuming the colour of their surroundings, and in the 
summer of 1909 he kindly gave me some eggs of Sam- 
byucaria, and suggested that I should test this’ species in 
the same way. "The results of the experiments show that 
it 1s one of the most sensitive hitherto investigated. I 
will briefly describe the experiments, before giving the 
details in tabular form. 
As is well known, the larvae of most Geometers feed 
only at night, and spend the day motionless in a twig- 
like attitude on the woody part of the food-plant, which 
in many cases they closely resemble, Prof. Poulton found 
* Trans. Ent. See, Lond,, October 5, 1903, and December 1892 3 } 
and “Colours of Anijals, " Lond., 1890, pp: 121, wz. 
TRANS. ENT, $00, LOND. 1911.—PART |, (TAY) 
