136 



DISTOMA HEPATIC UM, Linn. 



Plate XVI. 



Fig. 1. Adult fluke, natural size : la, young fluke, natural size. (Raillet.) 



Fig. 2. Eggs: a, egg with developing embryo; h, egg with embryo; c, egg-shell. 

 (Raillet.) 



Fig. 3. Ciliated and free embryo : «, perforating apparatus ;?), ocular spot. (Leuck- 

 urt.) 



Fig. 4. Encysted embryo found in snails. (A.P.Thomas.) 



Fig. .'). Diagram of digestive apparatus and nervous system : a, mouth sncker; h, 

 pharynx; c, ojsophagns; d, branches of intestine ; e, their branchlets; 

 /, nerve ganglia; g, ventral nerve. (Raillet.) 



Fig. 6. Limnams trnncatulus, the principal snail which is the larval host of the fluke 

 in Europe: a, natural size. (Raillet.) 



Fig. 7. Redia of Distoma hepalicum : a, mouth; h, pharynx; c, digestive tube; d, 

 the so-called germinative cells destined to produce cercarise. (Leuckart.) 



Fig. 8. Redia containing cercariic: a, mouth; h, pharynx; c, digestive tube ; d, d, 

 cercaria^ (Leuckart.) 



Fig. 9. Cercaria dissected from its cyst: a, anterior sucker; />, ventral sucker ; c, 

 pharynx; d d, branches of the intestine termin.ating in ca^ca. (Leuckart.) 



Fig. 10. Grass stalk with three encysted young flukes, a, a. (A. P. Thom;is.) 



Fig. 11. Free-swimming cercaria just before it is about to encyst. (A. P. Thomas.) 



Fig. 12. A slightly older stage than Fig. 11. (A. P. Thomas.) 



Fig. 13. Genital apparatus of the liver fluke : a, digestive tube ; 6, ventral sucker ; 

 c, anterior testicle; d, its deferent canal ; e, posterior testicle ; /, its def- 

 erent canal; g, seminal veside ; 7i, genital sinus; i, cirrhns pouch; /, 

 ovary; A;, oviduct; /, shell-gland; wi, yolk glands; n, longitudinal and 

 o, transverse yolk-gland canals; p, uterus; </, v.agina. (Raillet.) 



