THE DEVELOPMENT OP THE OVUM. Ill 



dominal segment are inserted into the oviduct before and above the bursa, 

 and a second pair from the same part of the eighth abdominal segment 

 are inserted into the oviduct between the bursa and its outlet. The 

 internal or membranous coat of the oviduct is continuous with the 

 integument at the extremity of the ovipositor. 



The function of the bursa is clearly to receive the male 

 fluid, but a few hours after copulation all the spermatic fila- 

 ments disappear from both the bursa and the oviduct. They 

 are then found in a dense mass, closely coiled together in the 

 capsules of the seminal receptacles. Nothing, then, remains 

 in the bursa but the two masses of coagulated albumen, one of 

 which occupies each lateral half. These gradually disappear, 

 either by deliquesence or absorption. The manner in which 

 the spermatic filaments are transferred from the bursa to the 

 receptacles is unknown, but the transference is probably 

 effected by their own movements. Upon one occasion I found 

 the upper part of the oviducts of a fly, which had been im- 

 mersed in spirit for four-and- twenty hours, filled with sper- 

 matic filaments, which were still in a state of active movement. 

 I suppose the insect had been captured immediately after 

 copulation, and that the spirit had not permeated the oviducts, 

 owing to the coagulation of the albumen around them, so that 

 the filaments, no longer directed into the ducta of the sper- 

 matic receptacles by the contraction of the oviduct above 

 their openings, found their way into the upper part of the 

 oviducts.* 



The external organ in the female consists of a lengthened 

 ovipositor, which is retracted when at rest within the posterior 



* In Burnett's Translation of Siebold, p. 450, note v., the spermatic 

 filaments are stated to be conveyed from the bursa of insects to the recep- 

 tacles by their ovrn movements, which agrees perfectly with the result of 

 my researches. 



