250 



MOVEMENT 



But although our theory may be generally true, 

 there are still certain details which remain to be 

 elucidated. For instance, in what way does the flight 

 of one insect differ from that of another, and what 

 function do the balancers subserve? Those singular 

 organs which from the point of view of comparative 

 anatomy would seem to be undeveloped wings, appear 

 to be indispensable for the flight of dipterous insects. 

 It occurred to us that these and many problems 

 could be solved by chronophotography, if it only 

 enabled us to catch a momentary view of the insect's 



Fig, 176.-- Schematic arrangement for illuminating insects when studying their flight. 



wing during its flight. But one can imagine that 

 the exposure would have to be very short to procure 

 a well-defined photograph of an insect's wing, when 

 an exposure of ^q-qd °f a second is too long in the 

 case of a bird's, although in the latter instance the 

 movement is much less rapid. 



Further, it is not improbable that with such a short 

 exposure, the time would be insufficient to imprint a 

 definite image on the plate. In order, then, to diminish 

 the period of exposure the fenestrations of the rotary 

 diaphragms must be made very small, and the light 



