106 THE VALUE OF COLOUR 



Professor Meldola observations and notes bearing 

 upon these subjects. Thus the following letter 

 given to me by Dr. A. K. Wallace, and now, by 

 kind permission, published for the first time, 

 accompanied a photograph of the chrysalis of 

 Papilio sarpedon choredon, Feld., suspended from 

 a leaf of its food-plant : 



July 9lh DOWN, 



BECKENHAM, KENT. 

 MY DEAR WALLACE 



Dr. G. Krefft has sent me the enclosed from Sydney. 

 A nurseryman saw a caterpillar feeding on a plant and 

 covered the whole up, but when he searched for the cocoon 

 [pupa], was long before he c d find it, so good was its 

 imitation in colour and form to the leaf to which it was 

 attached. I hope that the world goes well with you. Do 

 not trouble yourself by acknowledging this, 



Ever yours 



CH. DARWIN. 



Another deeply interesting letter of Darwin's, 

 bearing upon Protective Resemblance, has only 

 recently been shown to me by my friend 

 Professor E. B. Wilson, the great American 

 Cytologist. With his kind consent and that of 

 Mr. Francis Darwin, this letter, written four 

 months before Darwin's death on April 19, 1882, 

 is reproduced here l : 



1 The letter is addressed : ' Edmund B. Wilson, Esq., Assistant iu 

 Biology, John[s] Hopkins University, Baltimore Md., U. States.' 



