AC.ULEATA DEVELOPMENT 



(Fig. 4, A) placed two on the one, four on the other ; these are the 

 rudiments of the sting. In the course of development the 

 terminal three segments are taken into the body, and the external 

 pair of the appendages of the twelfth 

 body segment (the ninth abdominal) 

 become the sheaths of the sting, and 

 the middle pair become the director; 

 the pair of appendages on the eleventh 

 segment give rise to the needles or 

 spiculae. The sting -rudiments at an 

 earlier stage (Fig. 4, C) are masses of 

 hypodermis connected with tracheae ; 

 there is then but one pair on the 

 twelfth segment, and this pair coalesce 

 to form a single mass ; the rudiments 



of the pair that form the director are FlG . 4 .-Deveio P ment of sting of 

 differentiated secondarily from the 

 primary pair of these masses of hypo- 

 dermis. A good deal of discussion 

 has taken place as to whether the 

 component parts of the sting 

 gonapophyses are to be considered as 

 modifications of abdominal extremities 

 (i.e. abdominal legs such as exist in 

 Myriapods). Heymons is of opinion 

 that this is not the case, but that the 

 leg-rudiments and gonapophysal rudi- 

 ments are quite distinct. 1 The origin 

 of the sting of Hymenoptera (and of the ovipositor of parasitic 

 Hymeuoptera) is very similar to that of the ovipositor of Locusta 

 (Vol. V. p. 315 of this work), but there is much difference in the 

 history of the development of the rudiments. 



Dewitz has also traced the development of the thoracic 

 appendages in Hymenoptera.' 2 Although no legs are visible in 

 the adult larva, they really arise very early in the larval life from 

 masses of hypodermis, and grow in the interior of the body, so 

 that when the larva is adult the legs exist in a segmented though 

 rudimentary condition in the interior of the body. Dewitz's 

 study of the wing-development is less complete. 



1 Morph. Jahrb. xxiv. 1896, p. 192. 2 Zeitschr. wiss. Zool. xxx. 1878, p. 78. 



the bee : A and C, ventral ; B, 

 side view. A, End of abdomen 

 of adult larva : a, b, c, d, the 

 last four segments, c being the 

 eleventh body segment, 11 ; 

 b bearing two pairs, and c one 

 pair, of rudiments. B, Tip of 

 abdomen of adult bee : 9, the 

 ninth, d, the tenth body seg- 

 ment. C, Rudiments in the 

 early condition as seen within 

 the body : c, first pair ; b, the 

 second pair not yet divided into 

 two pairs ; b", c', commence- 

 ment of external growths from 

 the internal projections. (After 

 Dewitz.) 



