THE SENSES OF INSECTS — McINDOO. 481 



in front of them. In case of the honeybee, they might also be 

 sensitive to the weak currents of air caused by workers fanning. 

 It is possible that the sense hairs are not affected by these weak 

 currents, and, therefore, some method is badly needed to keep the 

 bees constantly informed that the fanners are working properly. 

 If this interpretation is correct, we here have another form of touch. 



Lying in the second antennal segment there is a peculiar structure, 

 knoAvn as the Johnston's organ. It consists of the modified articular 

 membrane (fig. 15, M) between the second and third segments, and 

 of many sense cells {( '), whose fibers (N) unite Avith peculiar knobs 

 (A*) extending inwardly from the articular membrane. Child has 

 described a similar organ in mosquitoes and thinks that it is an audi- 

 tory organ, but in the honeybee it is no better adapted to receive 

 sound vibrations than are the pore plates. In both organs the ex- 

 ternal membranes are well fitted for such a purpose, but the nervous 

 connections seem too crude,. 



Schon has described a structure in the tibiae of bees, which he re- 

 gards as an auditory apparatus. It is similar in internal structure 

 to those found in the tibiae of crickets and katydids, but it has no 

 external membrane as they have. The present writer has not yet 

 succeeded in finding all the details described by Schon. 



In conclusion, it may be that the sense of hearing in insects is on 

 ro higher plane than that advocated by Forel, who believes that in- 

 sects do not hear, at least as we do, but compares this perception in 

 them to that in deaf-mutes who feel the rolling of a carriage at a 

 distance. Forel says: 



Hearing is a physical sense. Sonorous waves, especially those of low sounds, 

 are nearer to large mechanical vibrations than luminous, caloric, or electric 

 waves. Hearing, therefore, must be in its origin connected with touch, but we 

 make a distinct difference between the perception of a very low sound by touch 

 and its perception by hearing. We must not forget that the specialization of 

 the organ of hearing has reached in man a delicacy of detail which is evi- 

 dently not found again in lower vertebrates. It is, I believe, the sense which 

 removes us most from the lower animals. In animals as high as fish the 

 auditory nerve is confused with other nerves, and the portion of the labyrinth 

 most specially affected by our audition, the cochlea, has disappeared. 



THE GENERAL SENSES. 



Among the general sensations might be mentioned those of 

 temperature, humidity, direction, and pain. 



The sense of temperature appears as much or as little developed 

 in insects as in ourselves. In our skin there are distinct tempera- 

 ture nerves, located in warm and cold points, but they do not end 

 in special nerve-end organs. Probably the same is true for insects, 



42803°— 22 31 



