Some ten years ago two veterinary surgeons of the department of the Aisne, Coulon and Ollivier, practising in a district where peripneumonia rages, made some extremely interesting observations on pneumonia in the ox. Their object was to distinguish between contagious peripneumonia and simple pneumonia during life, simple pneumonia having formerly been regarded as a non-contagious peripneumonia. Despite the rather unfavourable conditions in which ordinary practitioners are frequently placed, these gentlemen performed a work of great value. The facts which point to the occurrence of simple pneumonia are as follows:— =The disease= is not contagious. One may allow affected animals to mix with normal subjects without the disease being communicated. Pulmonary exudate from cases of simple pneumonia can be injected into the dewlap and hind quarters of young and adult animals, without pathological results. =The lesions= and =course= of simple pneumonia entirely differ from those of peripneumonia. =Causation.= Simple pneumonia is not common, and only occurs quite exceptionally in fat stock, or in milch cows kept in stables at a regular temperature, as in the north of France and near Paris. It occurs most commonly in working animals, which are exposed to variations in temperature and to chills. By causing vascular disturbance, chill favours microbic infection and visceral inflammation. Trasbot has described the case of an ox which, after having worked hard, and whilst freely sweating, was left exposed to the wind under a shed for about three hours. This animal contracted unilateral pneumonia the following day. Coulon and Ollivier have seen the disease in animals living in damp, low-lying valleys, or valleys exposed to the north wind, which are exposed in consequence to great variations in temperature. =The symptoms= follow almost the same course as in the horse, and one may distinguish three periods:— =I. Period of onset.= The symptoms which mark the onset of the disease are moderate fever, which progressively increases, and acceleration of respiration and of circulation. The number of the respiratory movements rises to twenty or twenty-five per minute, those of the pulse to fifty, sixty, or eighty. The conjunctiva becomes injected, and then of a yellow tint. At this period the appetite never disappears completely, rumination is regular, and there is neither tympanites nor colic. These general symptoms, which are not of special significance, are supplemented by more precise local symptoms—an abortive, difficult and painful, cough which is easily induced, and a whitish discharge. The rusty expectoration which is characteristic of simple pneumonia in the horse and in man has never been observed.