506 P. E. Keuchenius, 



In the protoplasm of the gland-cells I perceived above the nuclei, on the 

 side tunied to the lumen, a very delicate striping. 



Vasa deferentia and accessorial glands lead out on a com- 

 mon papilla in the vesicula seminalis. In this papilla there are 

 to be found two orifices; the cranial one is the common oiitlet for the 

 accessorial tubes, sois the caudalone for the two vasa deferentia. 



The vesicula seminalis is a rather large sack also invested 

 by a tunica externa and interna (fig. 1 ves, and fig. 6). The ex- 

 terna is very thin and shows small flat nuclei, while the interna 

 consists of a flat epithelium, in which round or oval nuclei are to be 

 Seen. The epitheUum is not a gland-epithelium and does not appear 

 as such, so, that it would seem to have had a secreting function during 

 the larva-stage. The lumen of the vesicula seminalis is composed 

 of a slimy mass, which gets only slightly stained and in which sper- 

 matozoa are floating (fig. 6 sp). This cranial blind sack must be 

 a temporary depository of produced sperm and fully deserves the 

 name of vesicula seminalis. Caudally the vesicula seminalis 

 narrows into the ductus ejaculatorius {iig. l d.ej). This bends 

 cranially and after one winding ends in the sacculus ejaculatorius 

 (fig. 1 sac), as Hewitt has named it. The sacculus finds an outlet 

 through a small canal, which I will call the ductus copulatorius 

 (fig. 1 d.cop). 



Sacculus and ductus copulatorius are covered outside by a 

 layer of cells, which is not an immediate continuation of the tunica 

 externa or interna of the ductus ejaculatorius, because their 

 structure differs. The inside lining of the sacculus and ductus 

 copulatorius is formed by a layer of very transparent and conse- 

 quently soft chitin (fig. 5 ch). Near the entrance of the ductus eja- 

 culatorius we see a bulge of the sacculus. In this bulge there is 

 to be found a small hoUow chitin rod, (fig. 1 ap) which is composed 

 of dark and therefore hard chitin, but on its entrance into the saccu- 

 lus, it continues in the soft chitineous lining of the latter. This organ 

 was first discovered by Brüel (2, p. 520) in Calliphora erythrocephala, 

 whilst also Hewitt has seen the small chitin rod in Musca domestica 

 and speaks of the "ejaculatory apodeme" (9, p. 432). The small chitin 

 rod is, on the outside, connected with the wall of the sacculus by 

 voluntary, transversally striped muscle-fibres. Very probably it is 

 an aid during copulation, in propelling the sperm and I propose to 

 call it i;he apothetes ejaculatorius. 



On either side of this organ, we see two very small tubes opening 



