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how little he was able to work out the material biologically. Evidently he is 

 not favourably inclined towards me, perhaps because I do not wish to accept 

 the numerous exaggerations and the false observations made by all kinds of 

 persons, who were not in the least accustomed to observe with that accuracy 

 and prudence which are necessary for biological observations, but which are 

 notwithstanding placed by him, without any critical intellect, simply on the 

 same level, and valued as scientifically proved facts. He reproaches me with 

 judging from preconceived notions; the only one I have, however, is, that I think 

 much expert criticism is necessary in judging of such observations ; but this 

 he does not seem able to understand. He himself, on the contrary, is entirely 

 governed by the preconceived notion that the above mentioned phenomenon 

 consists of real migrations of butterflies, a notion, evidently founded on the 

 Darwinian idee fixe that some useful purpose always occasions every biological 

 phenomenon, and that Nature endeavours to attain this end. The facts, also 

 those gathered by himself, do in no respect prove the correctness of this notion. 

 For it is not to be doubted that this flying in such an abnormally strong manner 

 as that which is spoken about here, in special circumstances — among which 

 a certain constant direction of the wind or also a strong gust of wind undoubt- 

 edly act a principal part — sometimes causes such a migration as well of a few 

 individual insects as of many, and casually even of whole swarms; and that 

 from it also sometimes the dispersal of a species may follow; but the superficial 

 spectator alone will draw the conclusion that this result has been the purpose 

 of that action. Nothing about this, however, has been proved, but there are 

 on the contrary several facts which indisputably show that sometimes at least 

 such purpose cannot possibly have been the cause of this swarming. Tutt 

 himself informs us that very big swarms of Hibernia defolaria L. have 

 repeatedly been observed in Heligoland, which swarms, however, exclusively 

 consisted of c/, which could not be otherwise, as the ? of this species have 

 no wings. Though in this respect the author also speaks of "migrations", it 

 is evident that in this case no migration and no dispersal of the species can 

 take place. Yet this species occurs from England and Heligoland to Japan 

 • and Vancouver's Island. But to such facts, though he mentions them himself, 

 he does not pay attention. Neither does he understand the value of the 

 common observation made in Ceylon, which he mentions also and which can 

 also be applied to other places, that, whence coming no one knows, whither 

 going no one can tell. Something to which we undoubtedly ought to pay 

 some attention, the more so as it is made in a region, as in Ceylon, where the 

 phenomenon is very often observed and has drawn the attention of many people. 

 While he adds, as is said, nothing of any significance beside his compilation. 



