MisceUaneous. 269 



this (Iclicicncy I investigated last summer by means ot' sections the 

 male sexual organs of certain Diptera, especially the genus La2>lirla. 



As we are already aware, the internal male genital apparatus of 

 Laj)hria (as of tlic Asilida3 in general) consists of two long spirally 

 coiled testicular tubes, two vasa deferontia, two long tubular acces- 

 sory glands, and a short ductus ejaculatorius. The testes are 

 loosely surrounded by a common envelope, which is of a dark red 

 colour and is well supplied with tracheae, lieneath the envelope 

 lies a fine layer of fat-granules. In structure this layer corresponds 

 to the membrane with which each follicle of the testis of the 

 butterfly is separately clothed, and, like it, it is in all probability 

 formed by the concrescence of the hypodermal layer of the tracheje*. 



The wall of the testicular tube consists of a thin but firm nucleated 

 membrane, beucath which there further lies a structureless mem- 

 brana proj)ria. Parietal epithelium is not found in the testis, 

 except at the spot where it passes into the vas deferens, where the 

 epithelium appears at first flattish, and then continually more and 

 more columnar. The vasa deferentia as well as the accessory 

 glands possess an external membrane similar to that of the testis, 

 while the ductus ejaculatorius is surrounded by a thick multilaminar 

 membrane, which is very feebly staiuable with carmine and con- 

 tains numerous nuclei. This membrane ; Iso envelopes the vasa 

 deferentia and the accessory glands at their transition into the 

 ductus ejaculatorius, in consequence of which the four tubes when 

 examined under a low power appear to be united for a space into a 

 common cord. The epithelium of the vasa deferentia is cylindrical, 

 but not columnar ; in the accessory glands the cells of the epithe- 

 lium are very columnar in places, and form a number of longitu- 

 dinal ridges, projecting considerably into the lumen of the gland, 

 between which the epithelium is flat. The ductus ejaculatorius ia 

 clothed with columnar cylindrical epithelium, the cells of which 

 contain large vacuoles in their peripheral extremities, and secrete a 

 thick chitinous intima. 



The trachea), which surround the testis in abundance, do not 

 penetrate into its cavity, just as is also the case in other insects. In 

 this respect I most decisively maintain my statements as to the 

 structure of the testis of the butterfly, in opposition to the objec- 

 tions of Tichomirow and Koschewnikoff f. In his paper on the 

 sexual apparatus of the humble-bee ("Drohne") Hcrr Koschewnikoff 

 indeed confirms my view, by alluding to the fact that in Apis the 

 trachea) do not penetrate into the cavities of the separate testicular 

 tubules. Further on, however, he writes : — " If we consider the 

 structure of the envelopes, the entire testis of the humble-bee is 



* N. Cholodkovsl<y, ' Der miintiliche Geschlechtsapparat der Lopidc- 

 ptereu,' St. Petersburg, 188G (in Russian). 



t Tichomirow, ' Eutwickkmgsgescliiclite von Boiuby.v mori,' Moskau, 

 1882 (in Russian) ; Kosclicwnikotl", ' Ueber den Run des Gesehlechts- 

 appanites der Drohne,' Moskau, 18!)1 (in Kussiau) ; Koschewnilvoff, '• Zur 

 Anatomic der niiiuiiliclicn (icsclileclilsdrgane der llonigbieue," Zool. 

 Anzciger, 18!>1, no. 3713, pp. o08-;j'J.l (Ann! vS: Mag. Nat. Hist. ser. H, 

 vol. ix., Feb. 1892, pp. 185-187). 



