1905.] FUNCTION OF THE ANTENNJi: IN INSECTS. 87 



for fi'om 5 to 10 minutes, after which it ceased to pay attention 

 to its injury and tried to fly. Attempts at flight generally 

 occupied another 5 minutes, and were invariably attended with 

 the same result. Each time the wings were opened, the insect 

 was raised for about an inch from the gi'ound and then turned 

 a somersault headforemost, like an acrobat. These somersaults 

 were always headforemost, the animal aHghting on its back and 

 struggling to its feet again. 



Each wasp made some score or more attempts at flight, always 

 with the same result. They then desisted and wandered slowly 

 about as if uncertain of their bearings, blundeiing up against 

 obstacles. Several were placed upon a window-sill, and each one 

 so placed, if it reached the edge in the course of its wanderings, 

 immediately fell ofT. 



Summarised, the results of the removal of the antennae in the 

 30 wasps were : — 



1 . Loss of the power of flight. 



2. Loss of the sense of direction. 



3. Very no'.iceable slowness in all movements. 



It has been suggested to me that the loss of flight and the 

 somersaults made lieadforemost evei-y time that flight was 

 attempted might have been due to the loss of a balancing weight 

 occasioned by the removal of the aiitennse, and that the experi- 

 ment should be made of fixing on false antennas in order to 

 ascertain whether the insect would thus regain its power of flight. 

 Whilst admitting that this explanation is possible, 1 would point 

 out that, if the want of balance were due to the absence of the 

 anterior weight of the antennfe, the insect would be more likely 

 to turn over backwards, on account of the over-balancing weight 

 of the abdomen, whereas the wasps experimented upon invaiiably 

 turned over headforemost. 



The conclusion to be drawn from these experiments is that, in 

 wasps, the antennae are equilibrating in function, and in this 

 respect they agree with Lowne's surmise, quoted above, and with 

 the experiments of Clemens on Samia cecropia, already cited. 



References. 



1. " ISTote sur le sentiment olfactif des Antennes." Ann. Soc. 



Entom. France, torn, vii., 1838. 



2. Die Fabrica et usu Antennarum in Insectis. 4to. Berolinii, 



1847. 



3. " Zum feineren Bau der Arthropoden." Miill, Archiv, 1855. 



4. " Ueber Geruchs- und Gehororgane der Krebse und Insecten." 



Miill. Archiv, 1860. 



5. ' The Anatomy of the Blowfly,' vol. ii. p. 590. 



6. " Die Organisation des Arthropodengehims." Zeitsch. f. w. 



. Zool., Bd. xxvii. 1876. 



7. " Memoire sur le Siege de I'odorat dans ks ArticuKs." Ann. 



Sc. Nat. ser. iii. Zool. torn. xiv. 1850. 



