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With these facts before us we may speculate as to the probable origin of the wings of insects. The views held by some are those of Gegenbaur, also adopted by Lubbock, and originally by myself.^[29] According to Gegenbaur:

“The wings must be regarded as homologous with the lamellar tracheal gills, for they do not only agree with them in origin, but also in their connection with the body, and in structure. In being limited to the second and third thoracic segments they point to a reduction in the number of the tracheal gills. It is quite clear that we must suppose that the wings did not arise as such, but were developed from organs which had another function, such as the tracheal gills; I mean to say that such a supposition is necessary, for we cannot imagine that the wings functioned as such in the lower stages of their development, and that they could have been developed by having such a function.”

Fig. 158.—Changes in external form of the young larva of Calotermes rugosus, showing, in A and B, the mode of origin of the wing-pads: A, newly hatched, with 9 antennal joints, × 8. B, older larva, with 10 joints, × 8. C, next stage, with 11 joints, × 8. D, larva, with twelve joints; the position of the parts of the alimentary canal are shown: v, crop; m, stomach; b, “paunch”; e, intestine; r, heart, × 16 3.—After Fritz Müller, from Sharp.