l62 



ZOOLOGY FOR MEDICAL STUDENTS 



CHAP. 



The ovary (Fig. 76, 0) is a much branched organ, lying usually in the 

 right (sometimes however the left) half of the body, about a quarter of 

 the distance from front end to hind end. It is continued towards the 

 mid-line of the body as a simple tube — the oviduct. While the ovary 

 produces the functional macrogametes, there is present also a great mass 



Fig. 75. 



" Flame-cells " (highly magnified). A, Planarian 

 worm : B, miracidium stage of Fasciola {Distoma) ; C, 

 Tape-worm [Taenia) ; D, a Polychaete (Phyllodoce) ; E, 

 Amphioxus. The highly evolved tubular type of flame-cell 

 shown in D and E is given the special name solenocyte. 



of female gonad which may be said to have degenerated, its cells being 

 no longer functional macrogametes but being simply yoIk-cells destined 

 to provide the zygote with a supply of food material. This degenerate 

 gonad is in the form of innumerable little spherical yolk-glands (y.g), 

 arranged in a broad band round the whole margin of the tody except 

 its extreme front end. In the fresh specimen this band is of a dark 

 colour, the yolk being dark greenish, but when the fluke is kept in spirit 



