XXXIX 



normally but white in white surroundings, and that the same occurs in the 

 case of the cocoons of Liparis auriflua W. V. and Rumia Crataegata L. 

 Bateson, however, in 1892 published in the Transactions of the Entom. Society 

 of Lotidon the results of some experiments conducted by him in connection with 

 the cocoon of Eriogastkr lanestris L. He obtained, indeed, the same results 

 but he expressed the opinion that the cocoon was normally dark coloured and 

 that the dark pigment is destroyed if during the formation ot the cocoon the 

 larva is placed in an abnormal condition through any disturbing factor, such 

 as being removed from the food plant when nearly full-grown or by the presence 

 of parasites. 



Dr. Harry Federley, in an article in the Mcddc/anden af Societas pro Fauna 

 el Flora Fennica, igog — igio, expressed yet another opinion; he also obtained 

 similar results in his experiments but he thinks these are to be attributed, 

 chiefly at least, not to the influence of the light but to that of the greater or 

 lesser humidity ; when the white cocoons, obtained in this manner, were sprinkled 

 with water they acquired the brown colour one or two days after. It is 

 difficult, however, in my opinion, to imagine that in the many experiments 

 which have produced the said results the lack of humidity could invariably 

 have played such a role without it being noted and I believe, therefore, that 

 this observation must be considered as an independent phenomenon. Bateson's 

 interpretation could not, of course be reconciled with the opinion of Poulton, 

 so strongly suggestive of the theory of mimicry, as regards the cause of this 

 phenomenon. The latter, therefore, at once proceeded to contest it and those 

 Transactions for the same year contain an account of new experiments on the 

 same larva carried out by him, in which it was subjected during the formation 

 of its cocoon to various disturbances without inducing it to become white. He 

 thus considers to have sufficiently refuted the interpretation by Bateson. 



It would appear to me, however, that Poulton may have been mistaken 

 and that Bateson's interpretation is really correct intuitively, if I may so call 

 it, /. c. without quite understanding its real bearing, while Poulton has over- 

 looked the principal disturbing factor in the case. Would not the presence of 

 bright, or at least white, light occasion an important disturbance in such a 

 heterocerous larva which in that conditions has continuously lived in daylight 

 but whose organisation of vision now becomes so changed that in the imago 

 stage it is only adapted for darkness and which, consequently, for its pupation 

 intentionally seeks dark places or protects itself against daylight by means of a 

 dark cocoon? I think this may be considered far from improbable and that 

 in this manner all these cases of white cocoons obtained on white paper or 



