m2 



2 INSFXTS AND HEREDITY 



been subjected to the strain of i^ravity and has responded 

 l)y tlic production of a definite shape, viz. one in which 

 the lono^ axis is parallel with the line of force. And )et 

 not a trace of any hereditary effect is manifest. Remove 

 the strain and the indi\idual is free, unbiased by the 

 forces exerted ui)on unnumbered ancestors, to assume 

 an entirely different shape. 



Vanessid pupae alone, so far as I am aware, have 

 been studied from this point of view. Figures of other 

 suspended Nymphaline pujjae, however, indicate that all 

 do not yield equally to the strain, althouo^h I believe 

 that all are to some extent aft'ccted. The pupae of 

 the Ari^j'nnidne (the' Fritillaries ') contrast in an interest- 

 incT manner with those of the I'aiiessidae in this respect. 

 The stron^l)-curved pupa o{ Ai'o^yjinis ao/aia figured by 

 W. Buckler ' was probably supported wholly or in part 

 by a leaf, as is suorcrested not only l^y the shape but the 

 plane of the surface of attachment, as shown in the figure, 

 and to some extent by the description. 



J'ariabic Protective Resevihlaiice hi Insects, 



The power which it is now known that many larvae 

 and puj)ae possess of changing their colour into corre- 

 spondence with the tints of each one of several possible 

 environments has been thousjht to favour the Lamarckian 

 interpretation of the origin of variation. Thus the late 

 George J. Romanes said of the evidence which had been 

 brought forward to prove the power in (juestion : 'It 

 has alwa)s appeared to me that the experiments them- 

 selves are among the most valuable which have hitherto 

 been made regarding the causes of variation ' ; ' an 

 opinion due, as th(! writer states, to his acceptance of 

 the ' Lamarckian concejHion '. 



On the other hand, I have never doubted that the 

 results are in the nature of a climax rather than a founda- 

 tion, that the)' represent the highest achievement of 

 Natural Selection in the protective colours of insects. 



' Ray Society, Zarrj<^ cf British BulUrJIits a?i(i Mollis, vol. i, Plate X, 

 fig. 3/y, 1886. 



- Xa/ure, vol xxxviii, 1888, p. 364. 



