ACULEATAy 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 



!>dy 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 G 



of the pair that form the director are FlG . 4. Development of sting of 



differentiated secondarily from the the bee : A and C, ventral ; B, 



side view. A, End of abdomen 



primary pair ot these masses 01 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 

 Hymenoptera) 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. 



i. Jahrb. xxiv. 1896, p. 192. - Zeitscltr. iciss. Zool. xxx. 1878, p. 78. 



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.) 



