BEHAVIOR OF SPIDERS AND OTHER INSECTS 385 



species unmutilated. Six species so mutilated that most of their 

 olfactory pores on the elytra and wings were prevented from 

 functioning responded from two to five times more slowly than 

 did the same species unmutilated, or with the antennae pulled 

 off." These results prompted the conclusion that the antennae 

 have no olfactory function and that the pores found on the 

 peduncles of the elytra, on the dorsal surfaces of the wings, on 

 the trochanters, tibiae, and sometimes the femurs and tarsi, 

 and perhaps on the mouth appendages, are the true olfactory 

 organs of beetles. This is in accord with the same investigator's 

 work on the Hymenoptera, which was reviewed in this journal 

 last year. 



These experiments of Mclndoo are painstaking and his anatom- 

 ical studies of what he calls olfactory pores are excellent; but, 

 the serious student, who is acquainted with the experiments of 

 Forel and others who " claim that the antennae are the organs 

 of smell," will not be convinced that the last word has been said 

 on the subject. They do not seem to have met the following 

 criticisms raised by Forel* several years ago: — " To demonstrate 

 the sense of smell, our two physical distant senses, vision and 

 hearing, must be eliminated with certainty. But that is not 

 sufficient. Innumerable chemical substances included in either 

 air or in water in a state of gas (free or absorbed) can, as is known, 

 and as I have already pointed out at the commencement of these 

 experiments (1878), while exercising in any way some corrosive 

 action, irritate nerve terminations other than those of olfaction, 

 and that (at least so far as concerns man) generally in a painful 

 or at least a disagreeable fashion." ' If we are content, as our 

 predecessors have often been, and as Graber is again, to bring 

 close to the animal certain substances which are odorous to us, 

 and see whether or not it avoids them, we have not demonstrated 

 olfaction at all. We have simply shown that these substances 

 have irritated the animal in one way or another. If the animal 

 comes up to them instead of avoiding them we have proof that 

 the irritation is agreeable to it. That nearly approaches olfac- 

 tion, but is by no means proof of it, for certain irritations can be 

 agreeable, without, for all that, being olfactive. It is necessary, 

 then, as I have said, to show that the irritation in question allows 



* Forel, August. The Senses of Insects. Translated by Macleod Yearsley. 

 Methuen & Co., London, 1908, p. 74-76. 



