LETTING THE BEES DO THEIR WORK 



than an hour a male butterfly of the same species 

 appeared on the street. When it reached the 

 high window its flight was retarded and it came 

 gradually toward the window. It flew into the 

 room and went up to the cigar box upon which 

 it perched. During the afternoon two other males 

 of the same species came to the box." 



A commentator observed that the experiment 

 makes it unequivocally clear that insects possess 

 an olfactory sense of almost inconceivable deli- 

 cacy. But the question as to what is the real 

 character of the stimulus that produces the sense 

 of smell, is one of the mysteries of science. 



"A substance like musk," he says, "may give out 

 a characteristic odor continuously for an indefinite 

 period, while the substance itself appears to lose 

 no weight. If particles of the odoriferous sub- 

 stance are really thrown off, these particles must 

 be almost infinitely tenuous. If, on the other hand, 

 the stimulus is due to the giving out of waves or 

 vibrations comparable to the waves of light or of 

 sound, the nature and other characteristics of these 

 manifestations of energy are absolutely unknown." 



Another experimenter has shown that ants will 

 follow a trail that has been made by other ants 

 bearing honey or sugar. The inference seems 

 obvious that the ants are following a very delicate 

 trail by the sense of smell. But perhaps it is well, 



[211] 



