OHIO STATE ACADEMY OF SCIENCE 



ated by immense gaps in geological time, all of the mechanism of a 

 tracheated flying arthropod. . 



That they were insects, that they had a tracheal respiration and 

 that they were capable of flight must be accepted else we may as 

 well call in question the whole mass oi knowledge baised on fossil 

 remains and which we so confidently accept as indubitable history 

 of the forms of life which peopled the earth in past ages. 



So much for tlie antiquity of the organ which we have in dis- 

 cussion and we may perhaps give pause for a moment to think how 

 long since and by what lowly creatures was the problem of aerial 

 navigation solved, a problem so attractive yet so elusive to the 

 powers of man. How then was the problem solved, what were 

 the factors conspiring to provide fox flight? 



It is haxdly necessary to remark that the wing of an insect is 

 a totally different structure from the wing of a bird. The most 

 superficial observation as well as the most elementary knowledge 

 of anatomy is sufficient for this. Their minute structure and the 

 pTOcess of their growth are, however, less familiar and in order 

 to secure a firm foundation for the discussion of the mode of 

 origin we must show something of this fundamental structure and 

 its agreement in different kinds of insects — a bit of dry anatomy, 

 a skeleton on which we may hang our threads of theory. 



The insect wing is fundamentally a sack the memhranous walls 

 of which are supported by a series of stiff rodlike "nen-es" or 

 "veins". A sacklike structure is easily seen in the expanding 

 wings O'f a moth or butterflv. As the rodlike supports fit to each 

 other above and below the fluid not used in the formation of the 

 v^dng is withdrawn into the body and the membrane hardens so no 

 separation between the upper and lower layer is noticeable. So 

 much mav easily be accepted as common to all insects. Is there 

 anv similar uniformity with regard to the number and arrange- 

 ment of the veins? 



In the different orders of insects we have quite diverse apparent 

 arrangement so that comparison ot a mature cockroach, dragon fly. 

 Cicada, house fly, beetle, butterfly and bee Avould show what appear 

 to be very different patterns of veins. So different indeed that 

 entomologists have applied very different sets of names to the 

 various nerves and while various attempts have been ni'ade to 

 establish uniform systems, such attempts have been largely unsuc- 

 cessful. Quite recently through elaborate studies of Professors 

 Comstock and Needham this uniformity has been much better 

 established and we can say with very great assurance that the wing 

 structure of all insects is reducible to a common plan or, to carry 

 out the logical conclusion from this, that the wings of all insects 

 are derived from one ancestral form. 



I need not here burden you ^Yii\\ the technical names of these 

 structures or of the detailed statement of their homology. Eefer- 



