In bovine animals the symptoms develop exactly as in sheep, though the cachectic period is uncommon and the injury done is often less important than in sheep. The patients exhibit irregular appetite, wasting without appreciable cause, anæmia, and even diarrhœa. In spite of excellent winter feeding they do not regain condition, and relative recovery only sets in with the approach of spring. Death from simple distomatosis is exceptional, but in animals so predisposed enteritis develops more easily, as do all forms of infection of intestinal origin. The disease is, however, also grave for bovines because successive reinfection occurs, and the disease may be prolonged for years. =Causation.= Distomatosis is due to one cause, viz., the entrance of embryo flukes into the digestive apparatus of herbivora. The adult distomata in the biliary ducts continually discharge large quantities of eggs, though the process is most active between February and June or July. The eggs are carried away with the bile and fæces and pass on to the pastures, where they continue their life cycle, thanks to moisture and the presence of stagnant water. The embryos, having escaped from the egg, enter the bodies of the snails found in or near stagnant water (_Limnæa truncatula_), become converted into sporocysts, and afterwards into rediæ and cercariæ. The cercariæ become encysted on the lower surface of blades of grass in damp pastures, whence they are transferred to the animals’ stomachs along with the grass itself. [Illustration: $1] As the _Limnæa truncatula_ lives not only in marshy regions, but also in all damp situations, the embryos of distomata are distributed over enormous areas, and the disease itself is equally widespread. The embryo, after ingestion, is set at liberty, and passes from the intestine into the innermost recesses of the liver, being guided up the bile ducts by the current of bile. At this point it attaches itself to the wall of the bile duct, passes through its various stages of evolution, and attains the adult form. It then begins laying eggs, and thus starts a new evolutionary cycle. The life cycle of _Distoma lanceolatum_ is not yet known, and this variety, moreover, is less widely distributed than the _Distoma hepaticum_. The bile ducts are more easily penetrated by the distoma in young animals, a fact which explains why calves and lambs are particularly affected. Adults present a less favourable nidus, a fact which renders them less easily infected, but does not entirely prevent the parasites from attacking them. Old animals, although unable to resist entirely, seldom harbour many of the parasites.