LXIV 



views of Mr. Jordan and being, moreover, entirely on his side on some points, 

 such as the rejection of the modern mutation theory, I am bound to declare 

 that I am unable to attach any scientific value to his opinions on the subject 

 of mimicr}' and that his lecture has by no means established the justness of 

 this theory. 



On August 4''' Mr. W. Schaus addressed the Congress, the title of his 

 discourse being " A qiioi sert le Mimetisvie ?" The speaker mentioned a great 

 number of lepidopterological observations made, in his capacity of field natu- 

 ralist, during a long stay in South and Central America, in connection with 

 the various assertions which have been made on the subject of mimicry; 

 observations with reference to the alleged facts — to which great weight is 

 usually attached in this respect — so much at variance that their connection 

 has completely dissipated his former belief in the value of so-called protective 

 colours. His communication on the subject was indeed of great importance. 

 Primarily because we do not meet here with such loose, isolated — and mostly, 

 therefore, as inaccurate as incomplete — observations which are so frequently 

 made by mere amateurs or zoological globe trotters possessed of but very 

 little sound lepidopterological knowledge, but with a deliberate expos6, the 

 result of observation during many years with a thorough knowledge of the 

 butterflies to which it has reference, which on that account deserves much 

 consideration, but also because these observations tally in so remarkable a manner, 

 even to minute details, with those carried out by myself and others in like 

 manner with reference to the Indo-Australian fauna, which have for the most 

 part already been published ; observations which from a believer in the theory 

 of mimicry have turned me into an antagonist. Such agreement of opinion on 

 this subject, evolved quite independently, having reference to a different tropical 

 fauna, and based on similar knowledge and experience, is surely of no little value. 



The statement, inter alia, by Mr. Schaus, that on several occasions he had 

 witnessed butterflies with so-called protective colours being attacked nothwith- 

 standing by enemies. Prof Dr. Seitz met by the observation that in order to 

 contest the theory of mimicry it is not sufficient to prove that a protective 

 colouring does not protect against all enemies but that it must be shown that 

 this would not avail against a single enemy and he quotes some instances 

 where, according to him, this is supposed to be the case. Prof Ssrrz thus 

 completely departs from the canons of proper scientic discussion. The burden 

 of proof would lie upon any one asserting that a specific colour affords pro- 

 tection, even if only against certain enemies, and it is only when this has been 

 demonstrated that the antagonist of this theory should show the fallacy of the 



