blSTOMATOSlS — LIVfiR FLUKE DISEASE— LIVER ROT. 



299 



lost. The sporocyst grows slowly at first, then more rapidly, and at the 

 end of fourteen days or so measures 0-5 mm. The germ cells mentioned 

 as existmg m the posterior portion of the miracidium now develop into 

 mdividuals of a third generation, known as— 



(e) Itnlue (Figs. 151 and 152).— The redite escape from the sporocyst 

 \Yhen the latter are from two weeks (in summer) to four weeks (in late 

 fall) old. Upon leaving the body of the sporocyst they wander to the 

 hver of the snail, where they grow to about 2 mm. long by 0-25 mm. 

 broad. Each redia consists of a cephalic portion, which is extremely 

 motile, and which is separated from the rest of the young worm by a 

 ridge; under the latter is situated an opening, through which the next 



Fig. 154. — Portion of a grass stalk with three encapsuled 

 cercariae of the common liver fluke [Fasciolri hepatica). 

 X 10. (After Thomas, 1883, p. 291, Fig. 13.) 



Fig. 155. — Isola-ted en- 

 cysted cercaria of the 

 common liver fluke. 

 X 150. (After Leuc- 

 kart, 1889, p. 286, 

 Fig. 142.) 



generation (cercariae) escape. The posterior portion of the worm is pro- 

 vided, at about the border of the third and the last fourths of the body, 

 with two projections. There is a mouth with pharynx situated at the 

 anterior extremity, the pharynx leading to a simple blind intestinal sac. 

 The redia, as well as the sporocyst, may be looked upon as a female 

 organism, and in its body cavity are found a number of germ cells, which 

 develop into individuals of the next generation, known as — 



(/) C'ercari(e (Figs. 153 — 155). — These organisms are similar to the 

 adult parasites into which they later develop. The body is flat, more or 

 less oval, and provided with a tail inserted at the posterior extremity. 

 The oral sucker and acetabulum are present as in the adult, but the 

 intestinal tract is very simple ; on the sides of the body are seen two 

 large glands, but the complicated genital organs of the adult are not 

 visible. The cercaria leaves the redia through the birth oj^ening, remains 



