"Some persons suppose that these parasites, which, from their particular form, were called flukes, were the cause of the rot. They are only the effect; yet it is to be remembered that they multiply so rapidly that they become the cause of further diseased action. Sheep, in the earlier stages of the affection, before their biliary ducts become filled with flukes, may be restored; but, when the parasites existed in abundance, there was no chance of the animal's recovery. Those persons who supposed flukes to be the cause of rot had, perhaps, some reason for that opinion. Flukes are oviparous; their ova mingle with the biliary secretion, and thus find their way out of the intestinal canal into the soil; as in the feculent matter of rotten sheep may be found millions of flukes. A Mr. King, of Bath, (England,) had unhesitatingly given it as his opinion that flukes were the cause of rot; believing that, if sheep were pastured on land where the ova existed, they would be taken up with the food, enter into the ramifications of the biliary ducts, and thus contaminate the whole liver. There appeared some ground for this assertion, because very little indeed was known with reference to the duration of life in its latent form in the egg. How long the eggs of birds would remain without undergoing change, if not placed under circumstances favorable to the development of life in a more active form, was undecided. It was the same with the ova of these parasites; so long as they remained on the pasture they underwent no change; but place them in the body of the animal, and subject them to the influence of heat, &c., then those changes would commence which ended in the production of perfect flukes. Take another illustration of the long duration of latent life: Wheat had been locked up for hundreds of years--nay, for thousands--in Egyptian mummies, without undergoing any change, and yet, when planted, had been found prolific.