114 



The Fly of Chironomus 



cuticle ; it consists of the gluten-gland and a pair of 

 spermatliecae. 



The gluten-gland extends between the ovaries for the 

 greater part of the length of the abdomen. It is of 

 elongate-oval shape, and externally smooth and undivided. 

 A cross-section shows that it is occupied by four longi- 

 tudinal segments (dorsal, ventral, and two lateral) of a 

 coagulable, transparent secretion, from which is derived 

 the bulk of the egg-mass (fig. 84). The wall of the gland 

 is rather thick, and shows in order, beginning from the 

 outside, a connective-tissue sheath, a layer of transverse 

 muscle-fibres, a space filled with granules in several 



Fig. 84.- — Transverse 

 section of gluton-gland 

 offemale fly, showing the 

 siibdivision of the secre- 

 tion into four masses. 



Fig. 85. — Spermatliecae and their 

 ringed ducts, irom i'emale fly. 



layers, a basement-membrane, and a lining ej)itlielium, 

 which in the pupa shows cells charged with secreted 

 matter. 



A ]3air of spermatliecae (fig. 85) lie on the ventral 

 surface beneath the gluten-gland ; they are derived from 

 rudiments contained in the eleventh segment, and form 

 nearly spherical capsules, about -25 mm. in diameter, 

 with short ducts, which converge to a common opening 

 close to that of the gluten-gland. The ducts have 

 muscular walls, and internally show a pseudo-tracheal 

 structure, similar to that often seen in the salivary ducts 



