55 



VARIATION IN VANESSA URTICM, L. : SEASONAL 

 (CLIMATICAL) AND LOCAL VARIATION IN V. 

 URTICM AND IN V. 10, L., BY WHICH THE 

 TWO SPECIES SHOW A TENDENCY TO MEET 

 IN FACIE S. 



By T. Reuss. 



(Concluded from p. 27.) 



Now, I believe that an entomologist who has digested some 

 cases of extreme seasonal dimorphism would also find it nourish- 

 ing to think that T". urticce would be capable of producing, under 

 suitable conditions, an extreme seasonal form which would 

 exhibit a perfect ocelUform facies like V. io. 



V. urticce ab. iofonnis, male {cf. ' Ent. Eecord,' pt. iv. 1909). 



The pigmentation of the left pair of wings is depicted as it appears when 

 the specimen is held up against the light. This shows the brightly trans- 

 parent white dots at the apex of the fore wing, which are placed in the same 

 way (both on the upper and under side, where they are yellowish), and are 

 of the same kind of transparency as similar spots in normal V. io (compare 

 also V. io ab. fischeri, Stdfss., figured vol. xlii. p. 311). In the hind wing 

 the density of the pigmentation and its distribution is very unlike that of 

 urticce, and much more like that of io, or abs. of io. The right wing pair 

 in the figure shows the aspect of the markings under the usual conditions 

 for comparison. The ground colour of the hind wings is a warm red-brown, 

 as in io ; the fore wings are orange-brown in colour. 



I bred this specimen — which might pass as a hybrid between urticce, 

 female, and io, male, just as V. io ab. fischeri, Stdfss., looks much like a 

 possible hybrid of to, female, and urticce, male — from ivild Continental larvae. 

 The pupa was exposed to the sun's direct rays, the heat of which like artificial 

 cold or heat is capable of overthrowing hereditary tendencies, and of thus 

 enabling the inherent io-forinitij to develop afterwards under stimulating 

 temperature conditions, representing exaggerated seasonal influence. The 

 "mechanism" of such aberrative development seems again to consist in 

 alterations of the blood, and blood pressure, regulating the diffusion of the 

 pigment in the wings, of a kind evidently for which V. urticce is j^redisposed 

 {inherent io-formity). Prof. Stephane Leduc, Nantes, has shown that even 

 "non-vital" chemical substances, if allowed to diffuse in a suitable medium, 



