986 NOTE ON THE FLIGHT OF INSECTS. 



NOTE ON THE FLIGHT OF INSECTS. 



By R. VON Lendenfeld, Ph D. 



In a paper (1) ou this subject, which was published a few years 

 ago, I opposed the view held by Marey and others, that the 

 changes in the shape of the wing during the flight was caused by 

 the mechanical action of the resisting air without any muscular 

 action of the insect itself coming into play. I found that the 

 radial nerves of the wings of the dragon fly are extended centri- 

 petally into the body, and that they are in connection with 

 numerous muscles and a complicated articulating skeleton, by 

 means of which arrangement each ray can be moved more or less 

 independently of the rest, whereby the shape of the wing is 

 changed. This view of the matter has recently been opposed by 

 some Physiologists who apparently did not take the trouble to 

 investigate the anatomy of the organs in question. 



Apparatus were constructed to demonstrate the mechanical 

 theory, Init these by no means prove the correctness of it. 



I have recently made some interesting observations bearing on 

 this point, which are particularly well adapted to prove the fallacy 

 of the mechanical theory, and can easily be repeated by everyone. 



If the animals are treated with certain poisonous substances, very 

 often a tetanus is produced. Such a poison is strychnine. Insects 

 are affected by substances, which are not injurious to other 

 animals in the way mentioned. The aromatic oil contained in the 

 blossoms of Pyrethrum carneum, roseum and ciaerarisefolium—the 

 essential part of " Insecticide," and turj)entine are such substances. 

 If a fly comes in contact with one of these substances a tetanus is 

 produced, the consequence of which is that the wings although 

 remaining in the ordinary position, change their shape in an 

 extraordinary manner. 



(I). Vo7i Lendenfeld. Der Flug der Libellen. Sitzungsberichte der 

 Kaiserlichen Akademie der Wissenschaften in VVein, 1881. 



