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CONTRIBUTIONS to the CHEMISTRY of INSECT COLOURS. 



By F. H. Perry Coste, F.C.S. 



(Continued from p. 252). 



V. — The Chemical Aspect. 



A. 



At the close of Section IV. I wrote,* " It now remains to 

 discuss the significance of these results, and offer such interpret- 

 ation of them as we can." That is the task that is to be essayed 

 in the remaining portion of these articles, and I am not uncon- 

 scious of the fact that my interpretations may have to run the 

 gauntlet of some criticism from readers of ' The Entomologist.' 

 So far, in recording experiments and observations, I have been 

 on fairly sure ground, but must now quit that for the region of 

 hypotheses ; far less certain ground, indeed, but yet without such 

 hypothesising the most complete and extensive experiments and 

 observations are almost valueless. We cannot mentally feed on 

 several hundred isolated individual facts ; such cannot be assimi- 

 lated, nor will they conduce to mental growth any more than 

 physically we can feed on atoms of carbon and nitrogen, &c, in 

 place of bread or meat. In both cases some preliminary elabora- 

 tion of the individual items is requisite ; and possibly, if we had 

 been suddenly set down to discover in what manner the physical 

 ultimates of food must be combined for our physical sustenance, 

 there would have been as many disastrous failures to prepare food 

 as there have been in all early attempts to work up a true mental 

 pabulum ! As Heidenhain truly says, " It is the fate of every 

 investigation into natural science that, after the establishment of 

 a series of connected facts which can be objectively observed, 

 an hypothesis must be established which brings these facts into 

 causal connection with one another." And this hypothesis must 

 be necessarily more or less tentative at first, until verified or dis- 

 proved by further experiments ; a working hypothesis, in fact, 

 which shall collect together for the present, into a compact and 

 assimilable form, all the individual facts, and suggest fresh 

 experiments the necessity for which would probably have not 

 otherwise been perceived. It is in this light — as indeed I have 

 before implied — that I wish my interpretations to be read ; and 

 if in succeeding articles I may appear to be advancing too confi- 

 dently theories for which some readers may think the present 

 evidence altogether too insufficient, I will, in anticipation, refer 

 them to this preliminary disclaimer. It is far more simple and 

 less cumbersome to explain this once for all than to preface every 

 individual hypothesis with "Let it, for the purposes of the present 

 enquiry, be considered probable that " ! After this candid 



* Entom. p. 223, 



