46 THE POPULAR SCIENCE MONTHLY, 



There is no such gradation between the most rapid undulations or 

 tremblings that produce our sensation of sound and the slowest of 

 those which give rise to our sensations of gentlest warmth. There is 

 a huge gap between them, wide enough to include another world or 

 several other worlds of motion, all lying between our world of sounds 

 and our world of heat and light, and there is no good reason w^hatever 

 for supposing that matter is incapable of such intermediate activity, 

 or that such activity may not give rise to intermediate sensations, pro- 

 vided there are organs for taking up and sensifying (if I may coin a 

 desirable word) these movements. 



As already stated, the limit of audible tremors is three to four 

 thousand per second, but the smallest number of tremors that w^e can 

 perceive as heat is between three and four millions of millions per 

 second. The number of waves producing red light is estimated at 

 four hundred and seventy -four millions of millions per second ; and 

 for the production of violet light, six hundred and ninety-nine millions 

 of millions. These are the received conclusions of our best mathe- 

 maticians, which I repeat on their authority. Allowing, however, a 

 very large margin of possible error, the world of possible sensations 

 lying between those produced by a few thousands of waves and any 

 number of millions is of enormous width. 



In such a world of intermediate activities the insect probably lives, 

 with a sense of vision revealing to him more than our microscopes 

 show to us, and with his minute eye-like ear-bag sensifying material 

 movements that lie between our world of sounds and our other far- 

 distant worlds of heat and light. 



There is yet another indication of some sort of intermediate sen- 

 sation possessed by insects. Many of them are not only endowed with 

 the thousands of lenses of their compound eyes, but have in addition 

 several curious organs that have been designated "ocelli " and "stem- 

 mata." These are generally placed at the top of the head, the thou- 

 sand-fold eyes being at the sides. They are very much like the audi- 

 tory organs above described so much so, that in consulting different 

 authorities for special information on the subject I have fallen into 

 some confusion, from which I can only escape by supposing that the 

 organ which one anatomist describes as the' ocelli of certain insects is 

 regarded as the auditory apparatus when- examined in another insect 

 by another anatomist. All this indicates a sort of continuity of sen- 

 sation connecting the sounds of the insect world -with the objects of 

 their vision. 



But these ocular ears or auditory eyes of the insect are not his 

 only advantages over us. He has another sensory organ to which, 

 with all our boasted intellect, we can claim nothing that is comparable, 

 unless it be our olfactory nerve. The possibility of this I will pres- 

 ently discuss. 



I refer to the antennm, which are the most characteristic of insect 



