Vol. 1.] 



Woodworth. — Wing Veins of Insects. 



23 



the head of the insect when making the record. If the insect 



were heading toward the direction from which the cylinder 



turns, which would be the natural thing to do, then Marey's 



records substantiate his theory. There is the possibility in 



all this work that the insect may reverse the action of the 



wings — which in some cases 



at least it seems to have the 



ability to do — and thus 



make false records, though 



this is not likely to happen 



often, for reverse motion is 



apparently always of short 



duration. Lowne's work is 



based almost entirely on 



the action of the wing in a 



dead insect, and is open to 



the criticism that there is 



no good evidence that the 



action studied is that which 



actually occurs during 



flight. 



The accompanying fig- 

 ures (Fig. 5), based on the 

 curves elaborated by von 

 Lendenfeldt, illustrate the 

 motion of the wing of 

 Agrion in flight. As seen 

 from above, the path ap- 

 pears to be practically the 

 same, whichever course the 

 wing follows; from the 

 side, however, the route of 

 the stigma is essentially 

 different, as is shown in 

 the diagrams. 



This insect, as well as the blowfly, the species studied by 

 Lowne, moves its wings much more nearly in a direction 

 parallel to the axis of the body than dorso-ventrally, but the 

 latter was doubtless the more primitive motion. The common 

 white butterfly, Pontia rapse, moves it wings in a nearly direct 

 dorso-ventral path. In such an insect the mechanics of flight 



FIG. 5. Diagram illustrating the flight 

 of Agrion. 



A. From above, the curved line .showing the 

 path of the stigma. B. From the side, accord- 

 ing to theory of von Lendenfeldt. C. From the 

 side, according to theory of Marey. 



