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Heymons, however, is inclined to believe that they are simply hypodermal outgrowths.

Fig. 186.—Ideal plan of the structure of the ovipositor to illustrate Lacaze-Duthiers’ view: b, 8th tergite; c, epimerum; a′, a, two pieces forming the outer pair of rhabdites; i, the 2d pair, or stylets; and f, the inner pair, or sting; d, support of sting; e, piece supporting the stylet; R, anus; o, outlet of oviduct. The 7th, 8th, and 9th sternites are aborted.—After Lacaze-Duthiers.

The first to study the morphology of the ovipositor was Lacaze-Duthiers, who referred their origin to the partially atrophied dorsal or ventral sclerites of one of the last abdominal segments; a view accepted by Gerstaecker^[37] (Figs. 186, 187). The present writer (1866), however, showed that the sting of Bombus was not formed of the reduced pieces of the segments themselves, but arose from special outgrowths on the ventral side of the eighth and ninth abdominal segments. These appendages he did not at first regard as the homologues of the limbs, until in 1871, after studying the origin of the spring of the Podurans (Isotoma), he found that it was a true jointed appendage and therefore a homologue of a pair of the styles forming the ovipositor of the winged insects, and that the three pairs of styles of the latter were homologues of the thoracic legs and cephalic appendages. The view was stated in the Guide to the Study of Insects. (See also Amer. Nat., March, 1871, p. 6.) Kraepelin also affirms that the styles of the ovipositor are segmental appendages and homologues of the antennæ, wings (sic), and legs.