The structure of the internal Genitalia of some male Diptera. 535 



Fig. 16. Obliquely transversal section of the testis. Rhingia rostrata. 

 X, pointed oblong bodies (perhaps degenerated spermatids). y, globular, yolky 

 elements; z, excrescence of the septum. 



Fig. 17. Transversal section of the unpaired vas deferens. Rhingia ro- 

 strata. n, nucleus. 



Fig. 18. Transversal section of the accessorial gland. Rhingia rostrata. 



Fig. 19. Longitudinal section of the vesicula seminalis. Rhingia rostrata. 



Fig. 20. Microphotograph of the male genital apparatus. Leptis scolopacea. 



Fig. 21. Diagram of the male gonads. Leptis scolopacea. 



Plate XXIV. 



Fig. 22. Longitudinal section of the proximal apex of the testis, in which 

 the protuberance, filled up with cysts is to be seen. Leptis scolopacea. y, cells 

 of a degenerated character. 



Fig. 23. Transversal section of the testis. Leptis scolopacea. f.h, fat-body- 

 tissue. ; y, cells of a degenerated character. 



Fig. 24. Transversal section of the glandulär part of the vas deferens. 

 Leptis scolopacea. l, central lumen; r, radial fissure. 



Fig. 25. Transversal section of the ductus ejaculatorius. Leptis scolopacea. 



Fig. 26. Diagram of the male genitalia. Dexia canina. 



Fig. 27. Longitudinal section of the testis. Dexia canina. deg.c, degenerat- 

 ing cysts; y, yolky bodies; n, nucleus. 



Fig. 28. Transversal section of the vas deferens. Dexia canina. 



Fig. 29. Transversal section of the ductus ejaculatorius. Dexia canina. 



Fig. 30. üiagram of the male gonads. Lucilia caesar. 



Fig. 31. Longitudinal section of the testis. Lucilia caesar. deg.c, dege- 

 nerated cyst; y, yolky bodies; n, nucleus. 



Fig. 32. Longitudinal section of the vas deferens. Lucilia caesar. 



Fig. 33. Transversal section of the accessorial gland-tube. Lucilia caesar. 



Fig. 34. Longitudinal section of the bladdery swelling at the commencement 

 of the ductus ejaculatorius. Lucilia caesar. Imn, lumen; pap, papilla, on which 

 the accessorial glands and vasa deferentia open. The papilla is only partly to be seen. 



Fig. 35. Traneversal section of the ductus ejaculatorius in its caudal part. 

 Lucilia caesar. 



Fig. 36. Section of the place, where the ductus ejaculatorius is entering 

 the sacculus ejaculatorius. Lucilia caesar. ep, epithelium (lining) of the d.ej. 



Fig. 37. Älicrophotograph of the male gonads. Sarcophaga carnaria. 

 Testes, vasa deferentia, accessorial glands and ductus ejaculatorius are to be seen. 



Fig. 38. Obliquelj' longitudinal section of the testis. Sarcophaga carnaria. 

 deg.c, degenerated cysts; y, yolky, globular bodies. 



Fig. 39. Spermatocyst with spermatids growing into spermatozoa. Sarco- 

 phaga carrmria. 



Fig. 40. Spermatocj'st with developed spermatozoa. Sarcophaga carnaria. 



Fig. 41. Transversal section of the vas deferens. Sarcophaga carnaria. 



Fig. 42. Transversal section of the accessorial gland. Sarcophaga carnaria. 

 A, Section at its beginning; B, Section near its end. 



Fig. 43. Transversal section of the ductus ejaculatorius at its beg^inning. 

 Sarcophaga carnaria. 



35* 



