DISTOMUM HEPATICUM 



1 1 



The sporocyst has an external cuticle, and beneath this an 

 external circular and an internal longitudinal layer of muscle 



4 



Fig. 2 



Stages in the life-history of Distomum kepaticum. i. An egg filled with large 

 vitelline cells, in which the segmenting ovum, em, is embedded ; o, oper- 

 culum. 2. Miracidium larva, showing the large ciliated cells, the eyespot 

 e, and the anterior papilla, pa. 3. A miracidium boring its way into the 

 tissues of a Limncea ; f-f, flame-cells. 4. A sporocyst containing one fully 

 developed and several developing rediae. The degenerate eyes are shown at 

 e, 5. A redia containing several daughter red ia^ in various stages of develop- 

 ment; m, mouth; ph, pharynx; ent, enteron ; r, muscular collar ; />, 

 posterior processes. 6. A cercaria ; ;. mouth ; s 1 , anterior, and s", posterior 

 suckers ; cs, cystogenous cells. (After Thomas.) 



