_Diagnosis._ This is based on the demonstrably highly contagious character of the disease, its rapid spread in a flock, and from the first to nearby adjoining flocks in summer, the short period of incubation, the constancy and nature of the diarrhœa, the speedy and great mortality, and the hemorrhagic lesions of comb, bowels, heart, lungs, liver, kidneys, spleen, and serous membranes. The demonstration of the bacterium in the blood and affected tissues is conclusive. Kitt points out that inoculation of a pigeon kills the bird in 12 to 48 hours, with dry yellow exudate in patches of from ½ to ¾ inch in diameter on the surface of the muscles, and yellow discoloration and nodular induration beneath. _Prognosis._ The mortality reaches 90 to 95 per cent. The negative chemiotaxis exerted on the leucocytes by the microbe, precludes defensive phagocytosis, and the progress of the deadly microbe is comparatively unhindered. Toward the end of a severe outbreak, and in certain mild epizoötics the recoveries are much greater. _Prevention._ All birds bought or otherwise acquired and all birds returning from shows should be quarantined for one week before being allowed to mingle with the flock. In summer this should be conducted inside fly screens. The manure should be burned, carefully secluded, or treated with dilute sulphuric acid. Buzzards and vermin as possible bearers of the infection should be excluded from poultry yards. So with human beings, dogs, etc., coming from infected places. In an infected flock the sick should be at once separated, killed and burned or treated with sulphuric acid. All manure should be treated in the same way. Buildings, yards and runs should be thoroughly cleaned and liberally sprinkled with a dilute sulphuric acid (2:100). If the birds can be divided up in small groups (say of 5) the appearance of the disease will only endanger that group. In small flocks or with very valuable birds it may even be well to take the body temperature morning and night and separate at once any bird showing a rise. Any diseased or suspected flock should be kept where its manure will not be washed into wells, running streams or ponds to which other birds have access. In a locality where the disease exists fowls should not be allowed to run at large. In winter this is very effective; in summer owing to the danger from insect bearers, it must be supplemented by the most scrupulous cleanliness of poultry houses and yards, and by a liberal sprinkling with dilute sulphuric acid, or other disinfectant, to be made especially abundant and frequent on the manure. Nocard cuts short the disease by injections, subcutem of a 5 per cent. solution of carbolic acid.