A TRUFFLE-HUNTER 235 



It is admitted that odour, such as affects our olfactory 

 sense, consists of molecules emanating from the body 

 whose odour is perceived. The odorous material be- 

 comes diffused through the air to which it communicates 

 its agreeable or disagreeable aroma. Odour and taste are 

 to a certain extent the same ; in both there is contact 

 between the material particles causing the impression 

 and the sensitive papillae affected by the impression. 



That the Serpent Arum should elaborate a powerful 

 essence which impregnates the atmosphere and makes 

 it noisome is perfectly simple and comprehensible. Thus 

 the Dermestes and Saprinidae, those lovers of corpse-like 

 odours, are warned by molecular diffusion. In the same 

 way the putrid frog emits and disseminates around it 

 atoms of putrescence which travel to a considerable 

 distance and so attract and delight the Necrophorus, 

 the carrion-beetle. 



But in the case of the Great Peacock or the Oak 

 Eggar, what molecules are actually disengaged ? None, 

 according to our sense of smell. And yet this lure, to 

 which the males hasten so speedily, must saturate with 

 its molecules an enormous hemisphere of air — a hemi- 

 sphere some miles in diameter ! What the atrocious 

 fetor of the Arum cannot do the absence of odour 

 accomplishes ! However divisible matter may be, the 

 mind refuses such conclusions. It would be to redden 

 a lake with a grain of carmine ; to fill space with a mere 

 nothing. 



Moreover, where my laboratory was previously saturated 

 with powerful odours which should have overcome and 

 annihilated any particularly delicate effluvium, the male 

 moths arrived without the least indication of confusion 

 or delay. 



