536 P. E. Keuchenius, The structure of the internal Genitalia etc. 



Fig. 44. Longitudinal section of the commencement of the ductus ejacu- 

 latorius. Sarcophaga carnaria. pap, papilla. 



Fig. 45. Longitudinal section near the end of the ductus ejaculatorius. 

 Sarcophaga carnaria. o.l, outer layer. 



Fig. 46. Section of the sacculus ejaculatorius and the ductus copulatorius. 

 Sarcophaga carnaria. o.l, outer layer. 



Fig. 47. Diagram of the male gonads. Musca corvina. (Modified after 

 Hewitt.) 



Plate XXV. 



Fig. 48. Longitudinal section of the testis. Musca corvina. 



Fig. 49. Proximal part of the ductus ejaculatorius. Musca corvina. A, 

 Transversal section; B, View on the outside of the gland-cells. 



Fig. 50. Transversal section of the distal part of the ductus ejaculatorius. 

 Musca corvina. 



Fig. 5L Diagram of the male genitalia. Pollenia rudis. 



Fig. 52. Longitudinal section of the testis. Pollenia rudis. 



Fig. 53. Transversal section of the accessorial gland. Pollenia rudis. 



Fig. 54. Transversal section of the ductus ejaculatoriift. Pollenia rudis. 



Fig. 55. Diagram of the internal male genitalia. Tipula oleracea. (Modified 

 after Dtjfoür.) ch.r, chitinous rod. 



Fig. 56. Longitudinal section of the testis. Tipula oleracea. A, Section 

 of the testis. B and C, Epithelium of the testis strongly magnified ; vac, vacuoles, 

 containing granules; x, globular bodies; y, granules formed by the epithelium; 

 n, nucleus. 



Fig. 57. Section of the bladdery widening of the vas deferens. Tipula 

 oleracea. One can see the cranial part of the vas deferens entering into the bladder. 



Fig. 58. Longitudinal section of the vas deferens after having passed 

 through the bladder. Tipula oleracea. t.ad.m, tunica adipo-membranacea; ep, 

 epithelium. 



Fig. 59. Transversal section of the accessorial gland. Tipula oleracea. 

 t.ad.m, tunica adipo-membranacea. 



Fig. 60. Transversal section of the beginning of the ductus ejaculatorius. 

 Tipula oleracea. pap, papilla; vac, vacuoles. 



Fig. 6L Transversal section of the caudal part of the ductus ejaculatorius. 

 Tipula oleracea. 



Fig. 62. Sagital section of the sacculus ejaculatorius, just at the entrance 

 of the ductus ejaculatorius. Tipula oleracea. ch.m, chitinous membrane; c.l, 

 cell-layer. 



Fig. 63. Diagram of the male gonads. Dicranomyia chorea. 

 Fig. 64. Longitudinal section of the testis. Dicranomyia chorea. c, cysts. 

 Fig. 65. Section of the bladdery widening. Dicranomyia chorea. 

 Fig. 66. Transversal section of the vas deferens after having passed through 

 the bladder. Dicranomyia chorea. 



Fig. 67. Transversal section of the accessorial gland. Dicranomyia chorea. 

 ^ Fig. 68. Longitudinal section of the vesicula seminalis. Dicranomyia chorea. 



