418 



PEOF. B. T. LOWITE ON THE STErCTURE AlTD 



On the Structure and Development of the Ovaries and their 

 Appendages in the Blowfly {CalUpJiora erythrocepJiala). By 

 B. Thompson Lowne, P.E.C.S., F.L.S., Hunterian Professor 

 of Comparative Anatomy in the Koyal College of Surgeons. 



[Eead 6th December, 1888.] 

 (Plate XXVIII.) 



1. Introductory. 



2. Development of the Ovaries and Ova. 



3. The Oviducts and their appendages. 



4. The structure of the Gum -glands. 



5. Theoretical Considerations and Conclusions. 



6. Bibliography. 



1. Introductory. 



The ovary of an insect is known to consist of a number of 

 ovarian tubes connected with a single outlet, the oviduct. 



The ova lie within a thin membranous tube, the tunica pro- 

 pria, and form an egg-string ; this is enclosed within a follicle, 

 the egg-follicle, the so-called peritoneal coat. In each egg-striug 

 three parts are usually recognized — the terminal thread, the ter- 

 minal chamber, and the egg- chamber or chambers. 



In the Blowfly each ovary consists of about a hundred ovarian 

 follicles, springing from the dilated anterior end, or calyx, of the 

 ovarian duct. When the ovary is mature (PI. XXVIII. fig. 8) 

 the terminal threads exist as mere rudiments {t.f.), and, properly 

 speaking, there are no terminal chambers. In the young ovary, 

 however (fig. 6), the terminal chambers are well marked (t.c). 



Much discussion is found in the writings of various authors as 

 to the nature and import of the terminal thread. 



Brandt (6*) maintains that there is no fundamental difference 

 between ovaries with and ovaries without terminal threads {I. c. 

 p. 21) — " these are mere prolongations of the ovarian tubes or of 

 their peritoneal investment. In the former case they have the 

 same morphological significance as the rest of the ovarian tube, 

 in the latter they are mere connective or suspensory bands." 

 My own observations have led me to exactly the same conclusion. 



Tlie Terminal Chamber (fig. 6, t.c.) is filled with small cells. 

 Stein (24) was apparently the first to distinguish the terminal 

 chamber as an important constituent of the ovary ; he calls it the 



* The numbers in parentheses foHowing authors' names refer to corresponding 

 numbers in the Bibliography given at the end of this paper. 



