New purchases should not only be selected from apparently sound and guaranteed stock, but they should be passed through an antiseptic dip on arrival, and then if possible quarantined in a special enclosure until they shall have proved their freedom from infection. A valuable ram may be placed with some lambs or yearlings in close quarters to ascertain whether he has brought the infecting matter with him. If all escape after some months the presumption is that he is sound. Perfect cleanliness of the fold should be maintained, and disinfectants may be freely used in it. The water supplies should be watched, rejecting streams that have drained sheep-pastures where there have been marked losses of lambs and ewes. Water from deep wells without any surface leakage is to be preferred. When new stock (ram, ewes, lambs) are of necessity mixed with the sound herd, a wide range, an open air life, and abundant dietary must be secured. The system that is full of strength and vigor can better resist the microbe and even throw it off entirely, whereas the weak, confined subject succumbs. For the same reason, the weak, emaciated and debilitated subjects should be at once separated from the sound flock, and kept in a special enclosure, in the open air, on a rich diet. Should they harbor worms, this seclusion is even more imperative. (See parasites of lungs, liver, stomach and bowels). Lignieres advocates immunization by serum prepared on the Pasteur method, but, as he has not divulged the exact technique of its preparation, it is impossible as yet, to give this an unqualified endorsement. It has this in its favor that the mature sheep, in full vigor of middle life, though in an infected area, usually resist the infection, while the young, old, debilitated and verminous suffer. Opposed to it are these considerations that are recognized by Lignieres himself;—1st, The acquired immunity is not perfect, as shown by occasional relapses in sheep that have survived a first attack; 2d, The serum inoculation is not only useless, but dangerous in animals that already harbor the germ; I may, add 3d, Any acquired parasitism or debilitating disease may tend to break down the immunity and prostrate the system under the infection. Lignieres advises that the serum treatment should be restricted to the new born lambs in infected herds, or herds in infected areas. The first three or four weeks after birth are to be preferred for the operation, though failing this it may still be ventured on, up to a few days before weaning. The longer it is delayed the greater the danger of a preëxisting infection, and of untoward results from the new access of infecting material, on the back of an infection which varies so extremely in its pathogenic potency. Even among the new born lambs, Lignieres would restrict the serum therapy to the strong, robust and healthy, and, if they survive the resulting fever, would repeat the _treatment_ after the hyperthermia has ceased.