PASCIOLA HEPATICA. 173 



changes. On the other hand, a fine, dry, open season, will tend to 

 check the growth and wanderings of the larvee, and thus render 

 the flocks comparatively secure. 



Considerations like these sufficiently explain many of the crude 

 theories which were early propagated concerning the causes of this 

 disease, and in particular, the very generally prevalent notion that 

 water, and water alone, was the true source of the disease. Intel- 

 ligent cattle-breeders and agriculturists have all along observed 

 that the rot was particularly virulent after long-contiaued wet 

 weather, and more especially so, when there had been a succession 

 of wet seasons. Co-ordinating with these facts, they Ukewise 

 noticed that the flocks grazing in low pastures and marshy districts 

 were much more hable to invasion than those sheep which pastured 

 on higher and drier groimds, but a note- worthy exception occurred 

 in the case of those flocks feeding in the salt-water marshes of our 

 eastern shores. The latter circumstance has suggested the common 

 practice of mixing salt with the food of sheep and cattle, both as 

 a preventive and curative agent ; and there can be little doubt 

 that this remedy has been attended with more or less satisfactory 

 results. The intelligible explanation of the good effected by this 

 mode of treatment we shall find to be intimately associated with a 

 correct understanding of the genetic relations of the entozoon 

 in question, for it is tolerably certain that the larv^ of Fasciola 

 hepatica exist only in the bodies of iresh water snails and small 

 aquatic animalcules. 



At the present time we are almost in a position to affirm that, 

 ere long, all the main facts relating to the origin and production of 

 the rot-disease will be satisfactorily brought to hght. In the 

 meantime, however, we beg to inform estate owners, agriculturists, 

 sheep-farmers, stock-masters, and all other parties interested in the 

 welfare of flocks and in the production of cheap and wholesome 

 food, that a true solution of this important economic question, in 

 so far as it relates to the production of healthy meat, can only be 

 obtained by the fiirther prosecution of our experimental researches. 



