350 Veterinary Medicine. 



and connected with the former a digestive canal having two 

 branches or csecae, and finally a delicate contractile tail of about 

 twice the length of the body. The body is 0.28 mm. to 0.3 mm. 

 in length and its skin is covered with fine spines. It escapes 

 from the redia by an orifice back of the ring, and actively bores 

 its way through the ti.ssues until it escapes .from the body of the 

 snail when it actively swims in the water, using its tail as a pro- 

 peller. Its life of freedom is, however, very short as it proceeds 

 at once to encyst it.self in the submerged vegetation or on that 

 which grows on damp soil. 



The encysted cercaria is found mainly on the stems of grass, 

 cresses, dandelion, dock, etc., where the swimming specimen has 

 fixed itself, lost its tail and covered itself with a glutinous exuda- 

 tion which hardens into a minute white .sac. These are usually 

 found on the lower parts of the leaves or stem, so that sheep, 

 which eat close, take in more and suffer to a greater extent than 

 other animals. Sheep with distorted jaws (undershot or over- 

 shot) are found to suffer less, as they can not crop the grass 

 short. Yet all herbivora are liable to acquire the parasite and it 

 may possibly be taken from the water as well as the vegetation. 



The cercaria from the cysts probably enters the gall ducts from 

 the duodenum, and can be found in the small ramifications of 

 these ducts in the liver, rolled upon them.selves, the ventral side 

 outward, and the oral sucker attached to the mucous membrane 

 to imbibe the blood (Railliet). Here they acquire sexual organs, 

 male and female in each individual, and grow to their full size in 

 about 6 weeks. 



Habitat. The distoma hepaticum infests the gall ducts of 

 herbivora, especially ruminants, and omnivora. The sheep is the 

 greatest sufferer, but they attack also the ox, goat, camel, deer, 

 antelope, hare, rabbit, great kangaroo, horse, ass, pig, elephant 

 and even man. 



Distoma Lanceolatum. Lancet Shaped Distoma. Smaller 

 than the distoma hepaticum (3 to 4 lines long hy ij4 lines broad), 

 the lanceolatum is also more pointed at both ends, but especially 

 the cephalic one, and is covered by a smooth skin. Both oral 

 and ventral suckers are large, the genital orifice is close in front 

 of the ventral sucker, the convoluted uterus and oviducts fill the 

 middle and hinder parts of the body, to which the contained ova 



