Chills, privations, irregular feeding, and badly-managed weaning may facilitate its development, but none of these causes, however important they may be, seem to play any other part than that of favouring the multiplication of the numerous varieties of microbes to be found in the intestinal tract. Vascular disturbance occurs, either as a result of direct irritation of the intestinal mucous membrane or of the action of toxic products contained in milk which has served as a culture medium for these microbes; this is followed by secretory disturbance, and the intestinal contents being modified in character, the microbes normally present undergo changes in number and quality. Inoffensive organisms assume pathogenic qualities and secrete toxic principles, normal digestion is disturbed, the intestinal defence becomes less perfect, toxic principles which the liver is incapable of destroying are absorbed, and diarrhœic enteritis is set up. =Symptoms.= Diarrhœic enteritis appears during the second week of life, towards the end of the first month, or even later. It is characterised by the passage of fæces consisting of mucus and containing little clots of milk. This is the first stage of alimentary diarrhœa, also termed “white diarrhœa” or “white scour.” It may prove unimportant; it may last a day or two and then cease. Most commonly diarrhœa increases and assumes a mucous and then a serous character, whilst the dejecta exhale a very characteristic repulsive smell. The excrement becomes greenish brown, and after several days or a week or more may appear blood-stained. The number of evacuations varies enormously, depending on the gravity of the condition. The ejected material is irritant, and the parts soiled by it, like the perineum, hocks, and back of the cannon bones, become slightly inflamed as though blistered; later, the hair falls away. The general health then begins to suffer. Fever remains moderate, but the mouth is pasty, the tongue coated, and the breath fœtid. The patients become thin, and lose their appetite and spirits. Palpation of the abdomen, especially of the right flank, is slightly painful, and the pulse is accelerated. The diarrhœa may spontaneously diminish if the animal’s constitution prove sufficiently strong; but if it follows its course, the little patient becomes weaker, eats less, the evacuations increase and are accompanied by tenesmus. In seven to eight days, in rare cases in four to five, the animal dies from toxi-intoxication of intestinal origin, or from infection resulting from intestinal germs, particularly the bacterium _Coli communis_, obtaining entrance into the circulation. On the other hand, the diarrhœa may continue for weeks. =The diagnosis= is easy, and there should be no difficulty in distinguishing this disease from dysentery and from umbilical phlebitis, which are also accompanied by diarrhœa.