80 GNATS OR MOSQUITOES — CHAPTER VI 



Micros. Science, iii., pp. 97-102), and he contends that the 

 entire antennae serves as an auditory organ, the atmospheric 

 vibrations being received by the long hairs of the antennas, 

 and so transmitted to the drum-Hke membrane which, as 

 already described, closes the front of the basal joint, and 

 thence through its contained fluid to the nerves lining its 

 cavity. According to this theory, the anterior membrane 

 is an actual membrana tympani, and the fluid within 

 corresponds in function to the endolymph, contained in the 

 cavities of the internal ear of the higher animals. It has 

 been further pointed out that the hairs of the verticils of 

 the male Mosquito respond to the musical note given by 

 the vibrations of the wings of the female insect. Professor 

 Lubbock (" The Senses of Animals," p. 115) seems to 

 regard with some favour Johnstone's idea on this point, but 

 antennae having this form of basal joint are not very common 

 in insects, and if it be really a tympanum it is certainly a 

 very exceptional arrangement. The articulation between 

 the first and second antennal joints is capable of very free 

 motion, so that at this point the entire organ can be moved 

 to considerable angle in any direction, while the extent of 

 mobility between the latter and the succeeding ten joints 

 is much more limited. Except in tlie very aberrant Deino- 

 kerides cancer, in which the second is as long as several 

 of the succeeding ones, from the second to the twelfth 

 pieces inclusive, the joints closely resemble each other, 

 forming a moniliform series of short cylindrical pieces of a 

 length but little exceeding their thickness. From the base 

 of each springs a verticil of hairs, numerous (about forty) 

 and long in the ^ , and shorter and fewer in the ? . It is 

 more than probable that these hairs in the <? are really 

 chordotonal, auditory organs, as there is no doubt that they 

 respond to the note of the female wings, and it is the func- 

 tion of the male in these insects to seek out the female, but 

 the acceptance of this does not involve that of Johnstone's 

 theory of a tympanic function for the basal joint. The 

 last two joints greatly exceed the others in length, forming 

 in the male, together, much more than a third of the entire 

 length of the organ. The basal verticil of the penultimate 



