Fluke disease first makes itself apparent in the sheep one or two months after infection. If the sheep does not die the parasites often remain in its liver till the next spring. The liver of a single sheep may contain from 200 to 250 individuals. They live in the various branches of the bile-duct, and the irritation they set up first causes an unusual quantity of blood to flow to the liver. Inflammation and internal bleeding may result, and gall stones are deposited in the thickened walls of the biliary passages. The flow of bile from the liver is made difficult or impossible. Later on, the parasites draw so much blood from the liver that this organ is very insufficiently nourished, so that no more bile is secreted, and the liver substance shrivels up. In consequence of these changes the digestion is incomplete, and the whole body of the sheep is very insufficiently nourished. The diseased sheep are therefore sluggish and enfeebled; they eat little, but drink a great deal, and suffer from poverty of blood. Their wool gets dry, and does not hold together, and they become emaciated. Dropsy and diarrhœa set in, and jaundice often makes its appearance. If a sheep is infested by a tolerably large number of flukes, death is almost always the final result. “The best _preventative_ is a trustworthy and careful shepherd,”[5] who will not let the sheep feed in spots where previous experience shows the disease is usually contracted during damp summers. Furthermore, sheep badly infested should be slaughtered as soon as possible, so that the flukes they contain may not get to the egg-laying stage. Sick sheep should be fed with nourishing food (various kinds of hay, oats; with addition of cooking salt), so that young sheep containing but few flukes may get back their strength, while this treatment will make the badly infested sheep die more quickly. Footnote 5: Spinola. Oxen are also frequently affected by fluke disease in many regions, other animals to a less extent. The =Small= or =Lancet-shaped Liver Fluke= (_Distoma lanceolatum_) is about three-eighths of an inch long, one-tenth of an inch broad, thin, and lancet-shaped. Lives, like the preceding kind, in the liver of the sheep. Development unknown. =Fourth Sub-Kingdom: MOLLUSCA= (MOLLUSCS).