FASCIOLA HEPATICA 341 



entry of the larvae. Emaciation now becomes very marked, the 

 skin and mucous membranes blanched, temperature variable and 

 marked by an irregular curve ; respiration laboured and quick ; 

 appetite regular; abortion frequently occurs in pregnant ewes; 

 pressure on the back causes the animals to fall ; local cedemas 

 occur, the most perceptible in the submaxillary space, extending 

 below the larynx and over the cheeks and parotids (called 

 " bourse," " boule " in France; "watery poke" or "cockered" in 

 England). Death usually occurs at this period, but a fourth 

 stage may occur. 



[The fourth period is the PERIOD OF MIGRATION OF THE 

 FLUKES. This is a period of convalescence and recovery, generally 

 in May and June. F. V. T.] 



Oxen suffer less in general, but even in these animals "stray" 

 hepatic flukes are occasionally found in the lungs, enclosed in thick- 

 walled cysts. 



Pathological Anatomy. The bile-ducts are conspicuous on the 

 surface of the liver. They are thickened and much dilated and in 

 parts saccular, and considerable atrophy of the liver cells accom- 

 panies the condition. Histologically there is immense proliferation 

 of the epithelium of the bile-ducts leading to "adenomata." 



The LIFE -HISTORY of the liver fluke was discovered by 

 R. Leuckart and P. Thomas. According to these investigators the 

 elongated miracidium (fig. 131, a) ciliated all over develops from the 

 eggs a few weeks after the latter (fig. 142) have reached the water, and 

 after it has become free the embryo penetrates and becomes a sporo- 

 cyst (fig. 131, b) in a water-snail (Limnceus tnincatulus, MUll. = 

 L. minutus, Drap.) that is common in fresh water, and can live in the 

 smallest collection of water as well as in fields that have been flooded. 

 The sporocyst first of all produces rediae, which remain in the same 

 host (and under certain circumstances, e.g. in summer, these develop a 

 second generation of rediae), and these finally form cercariae (fig. 134). 

 The latter become encysted on blades of grass and are taken up by 

 the respective hosts with their food; this takes place towards the 

 end of summer, while the sheep feeding on the pasture land in the 

 spring spread the eggs of the fluke, and sometimes the fluke itself, 

 by passing them with their faeces. 



In districts where Limnceus truncatulus is absent, analogous 

 species act as the intermediary hosts, of which one example 

 according to Lutz is Limnceus oahnensis in the Sandwich Islands. 



[The host in Europe is Limnceus truncatulus. This snail 

 extends from Siberia to Sicily and Algeria, and according to 

 Captain Hutton is a native of Afghanistan. It also occurs in 

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