_Etiology._ As already stated this disease is due to the presence of a microörganism, the _bacillus mallei_. Many secondary causes, however, contribute to its propagation. The activity of movement and commingling of horses has been already noticed. Crowding in close yards where the animals bite each other, snort out the virulent discharges on each other and eat and drink from the same troughs, leads to a rapid extension. Even on the western ranges where the disease tends to be mild, Billings observed a deadly extension when yarded during winter storms. Debility from chronic ill health, starvation, overwork and damp, dark, draughty stables, is so conducive to the disease that it was at one time considered as the sole cause. Close confinement in impure air is at once a cause of increased susceptibility and a means of concentration and transmission of the poison. Hence confinement, between decks, of military and other horses, carried by sea, is a source of wide extensions. On the other hand insular places from which strange horses are excluded or into which they are admitted under careful inspection and quarantine have succeeded in preserving immunity. Australia, Tasmania and New Zealand are examples. _Bacillus Mallei._ Christot and Kiener claimed to have found a bacillus in the lesions of glanders in 1868. In 1881 bacilli were found by Bouchard in a glander abscess in man, and these were cultivated _in vitro_ and inoculated in a number of animals, by Capitan and Charrin in 1882. Independently in the same year (1882) Löffler and Schütz discovered the bacillus, cultivated it _in vitro_, and successfully inoculated it on animals. The microbe is rod-shaped, 2 to 5μ long, by 0.5 to 1.4μ thick, the same length as the bacillus tuberculosis but thicker. It is nonmotile, ærobic (facultative anærobic) and grows readily in a variety of culture media at a temperature of 37° C. On neutral bouillon of the flesh of horse, ox, calf or chicken with or without peptone, it grows readily, producing cloudiness in one or two days. In peptonized gelatine it forms a whitish flocculent mass. On glycerine agar with milk it forms in 48 hours a milk white layer, changing to yellowish brown. On potato it forms long slender filaments, in yellow, viscous, glistening colonies, changing to fawn and darker. It grows best at 35° to 39° C. and growth ceases below 25° C., and above 42° C. It stains tardily in aniline colors, and not at all by Gram’s or Weigert’s, but will readily take Kuhne’s stain prepared as follows: take of phenic acid in solution (5:100) 50cc., absolute alcohol 10cc., and 1 to 2 grammes methylin blue. The stain is very easily bleached by acid, differing in this from the bacillus tuberculosis. For decolorizing Löffler recommends 10cc. distilled water, 2 drops of strong sulphuric acid, and 1 drop of a 5 per cent. solution of oxalic acid. Sections should be left in this not longer than 5 seconds. The bacillus often