29G 



DISEASES OF THE LIVER. 



development ; (3) a shell surrounding the germ cell and vitellme cells, 

 and provided at one end with a cap or operculum. The eggs escape from 

 the uterus of the adult through the vulva, are carried to the intestine of 

 the host with the bile, then pass through the intestines with the contents 



Fig. 146. — Egg of the common liver 

 fluke (Fasciola heimtica), exa- 

 mined shortly after it was taken 

 from the liver of a sheep. At one 

 end is seen the lid or operculum, o ; 

 near it is the segmenting ovum, e ; 

 the rest of the space is occupied 

 by yoke cells which serve as food ; 

 all are granular, but only three 

 are thus drawn. X 680. (After 

 Thomas, 1883, p. 281, Fig. 1.) 



^.- 



-^ 



Fig. 147. — Egg of the common liver 

 fluke containing a ciliated embryo 

 (miracidium) ready to hatch out : 

 d, remains of food ; e, cushion of 

 jelly-like substance ; /, boring pa- 

 pilla ; h, eye-spots ; A-, germinal 

 cells. X 680. (After Thomas, 

 188:-5, p. 283, Fig. 2.) 



of the latter, and are expelled from the host with the ffecal matter. Many 

 of them become dried, and then undergo no further development; but 

 others are naturally dropped in the water in marshes, or, being drojjped 

 on dry ground, they are washed into water by the rain, or are carried to 

 a more favourable position by the feet of animals pasturing or passing 

 through the fields. After a longer or shorter period of incubation, which 



