CURRENT NOTES. 141 



are divisible into two classes (1) presumably attractive, (2) presumably 

 repulsive or protective, he describes in detail the scents of a large 

 number of insects as " agreeable " or the reverse, finding apparently, 

 in our human appreciation of the scents, the necessary evidence that 

 the scents really are "attractive " or "repulsive and hence protective," 

 as the case may be. It is just here that the non-enthusiastic, but 

 willing-to-believe-in-scent entomologist, comes in. He asks for the 

 outside evidence that the humanly-agreeable scent is " attractive " and 

 pleasant to the taste (!) of birds, reptiles, and other insects (which are, 

 possibly, after all the greatest enemies of insects), and the other 

 " repulsive " to them. 



The record of the existence of the scents themselves is most useful, 

 and the knowledge of their effect on the average human nostril 

 valuable, but we do not find in the paper a single atom of outside 

 evidence that the " scents that are agreeable to the average human 

 perception are presumably attractive," nor that those that are similarly 

 " disagreeable, or even disgusting to the average human perception, 

 are necessarily repulsive and protective." Surely even the appreciation 

 of scents by humans is largely the result of education, and estimated 

 as agreeable or the reverse by different individuals, for the differing 

 intensity of the same scent may produce pleasure or nausea in the 

 same individual. Even the word " attractive," as here used, is open 

 to objection, as, set in opposition with the word "repulsive," it suggests 

 .that its mere existence is as superlatively dangerous to the insect 

 possessing it, as the existence of the " repulsive" scent is assumed to 

 be superlatively useful to the insect possessing it. Surely " natural 

 selection " would long since have attempted to get rid of so disastrous 

 a feature as this " attractive " scent were this so ; but, of course, no 

 one really believes that it is, and our ignorance concerning these 

 matters is colossal and still wanting almost entirely in observed facts 

 in the field. In this, as in most things bearing on entomology, purely 

 or largely of a speculative nature, it is so easy to believe what we want 

 to believe, concerning things that are bound, by their nature, to be 

 quite nebulous in our mental picture. 



To read this paper, one might suppose that the details of the 

 subject were " now so familiar," that it really was " not necessary to 

 give the new evidence in great detail," and that there was no need for 

 the observer to " concern himself with the special organs which are 

 involved in elaborating or distributing the scents," when, as a matter 

 of fact, it is very necessary to recognise fully how infinitesimal is our 

 knowledge both of the nature of the scents, and the purpose or 

 purposes they subserve ; whilst, as to the biological origin of the 

 scents, we are still in absolute Cimmerian darkness. The human out- 

 look on entomology is so easy — true natural history so difficult. We 

 do not wish to belittle the work done by Miiller, Scudder, Packard, 

 and more recently by Dixey, but after all what has been done is a 

 mere scratch on the surface of a subject, the extent of which, and the 

 difficulties of approaching which, we evidently fail to appreciate. 



As to the purely speculative side of the observations, one illustra- 

 tion is as good as a dozen. One section is entitled, " Butterflies 

 bearing the marks of foes." In this, 14 Neotropical butterflies 

 are noted as having been captured with symmetrical, or nearly 

 symmetrical, pieces out of the wings on either side ; 21 others 



