Beceftaculum Seminis of Bees and Wasps. By F. B. Cheshire. 13 



the tremendous drain upon her for egg-formation can be met by- 

 such a small alimentary canal as leaves abundant room within 

 the abdomen for her extremely developed ovaries. 



Eemoving cautiously viscus after viscus, we find at length the 

 wasp ovaries placed well back, consisting of seven or eight ovarian 

 tubes, each (plate II. fig. 6, T*) quite separate from one another, 

 while those of the queen bee are, as formerly stated, remarkably com- 

 pact (plate I. fig. 1, 0). The egg-tubes in the wasp are associated 

 with extremely strong and large tracheae, having for one of their 

 objects undoubtedly the holding of the ovaries in accurate position 

 whatever may be the state of the alimentary canal or the movements 

 of the insect. The ovaries of the bee fill entirely the fore part of the 

 abdominal cavity, the walls of which retain them in position and 

 render any such tracheal strappings unnecessary; but there are 

 other reasons also for this difference in arrangement. It might at 

 first appear that the closely placed ovarian tubes of the bee could 

 not be duly irrigated by the circulating fluid, but further investiga- 

 tion shows that this near contiguity of the tubes mainly secures 

 the copious blood-flow which the rapid growth of the contained 

 eggs demands, for the dorsal vessel, by constantly pumping the 

 blood towards the head, induces a return flow through the petiole 

 connecting the thorax with the abdomen. Against this petiole the 

 small extremities of the ovarian tubes are gathered, tiny interstices 

 are kept between them by the intervening small tracheae, and so 

 amongst all the tubes of the two ovaries, the blood must insinuate 

 itself and pass on rapidly to return as much as the ever-beating 

 dorsal vessel is propelHng forwards. The wasp ovaries, on the 

 contrary, stand in the middle of the widest part of the abdomen, 

 and here the blood-flow is necessarily sluggish, but for this com- 

 pensation is afforded by the very wide tracheae, making due nutri- 

 tion and oxidation certain ; and further, the ovarian tubes are kept 

 from falhng into contact by a stifiish ring r, fig. 6, placed at the 

 upper extremity of the oviduct. The very dissimilar egg-organs in 

 both insects are therefore probably as well supplied as though the 

 creatures possessed a vascular system. The walls of the oviducts 

 (fig. 6, D) we discover to be crowded with tracheae, and supplied 

 well with nerves and very numerous muscular fibres which are 

 mostly arranged in two systems (a longitudinal and a transverse). 

 Stiffly jutting out from the common oviduct we find a parenchy- 

 matous body at the extremity of which is placed the spermatheca 

 sp carrying the mucous gland mg. These parts are held in 

 position by numerous tracheae and muscular attachments, and by 

 the lateral support given by the large abdominal ganglion of the 

 principal chain, as stated previously with regard to the bee. If 



* The eggs in the figure are not nearly fully developed. 



