526 P- E. Keuchenius. 



epithelium are thin and provided with very flat nuclei, which are 

 placed at their base, whilst the protoplasm above these nuclei shows 

 a fragile striping. In tbe protoplasm I observed vacuoles (fig. 60 vac) 

 of different sizes. On the inner surface of the epithelium I saw a thin 

 seamed edge, which as it appeared to me, was formed by the expelled 

 secreta {fig. 60). This bladdery swelling continues, also on the cranial 

 side (fig. 55), in the ductus ejaculatorius {d.ej), which runs caudally, 

 whilst twisting several times. 



The ductus ejaculatorius is invested by a tunica externa 

 and interna (fig. 61). The externa {ex) is only very thin; the in- 

 terna (in) is an epithelium, which is rather flat. Finally the ductus 

 ejaculatorius enters the sacculus ejaculatorius (fig. 55 sac). 



Up tili now I have succeeded in following exactly the course of 

 the genitalia of Tifula oleracea in my sections. The sacculus eja- 

 culatorius is a thick and very hard, chitinous bladder, on which is 

 fastened a spiral and hollow chitinous rod (fig. 55 ch.r) already described 

 by DuFOUR (6, p. 218). It has become clear to me from my sections, 

 that the sacculus ejaculatorius (a section of which is drawn in 

 fig. 62) has a very complicated structure., The chitinous consistency 

 of the sacculus and of the things which are found in it, and of the 

 chitinous rod, is so hard, that the sections were mutilated during 

 microtomical cutting, so that I have not succeeded in following the 

 structure and the further course of the genitalia. 



Dicranomyia chorea Meig. (Fig. 63 — 68), 

 The male gonads are composed of one pair oftestes, vasadefe- 

 rentia, accessorial glands, vesicula seminalis, ductus eja- 

 culatorius and sacculus ejaculatorius (fig. 63). 



The testes (fig. 63 ^ are two oblong bodies, which have their 

 Situation dorso-laterally of the gut. In respect to each other they 

 are placed asymmetrically i. e. the right testis a little more cranially 

 than the left one. The testes are enclosed by fat-body-tissue, 

 which has intimately coalesced with them. I have not been able to 

 trace a tunica externa and interna; in other words the testes 

 are only covered by one investment, which is a flat epithelium and is 

 to be observed over the whole surface of the testes (fig. Q4:ep). Con- 

 sequently there is no question ofamembrana propria on the pro- 

 ximal part of the testes. The epithelium is intimately connected 

 with the surrounding fat-tissue. Against the surface of the testes 

 are to be found tracheal trunks. The Contents of the testes (fig. 64) 



