Pulmonary atelectasis, a common postoperative complication, is associated with high fever, tachycardia, and a rapid respiratory rate. The stimuli for these changes and the mechanisms whereby they are effected are the topics of this paper. An experimental method for production of the clinical syndrome will be described first and then the investigation of the physiological disturbances. The physiological studies consist of two aspects: the changes that cause fever, and the stimuli for these changes.
The experimental animals were mongrel dogs of both sexes, weighing 20 to 40 lb. They were devocalized and allowed to recover for one week in the animal house before use in the experiment. The diet consisted of standard animal chow with the addition of meat five days a week. Anesthesia was induced in most instances by the intravenous injection of hexobarbital (Evipal *) in a dose of 15 mg/lb. This gave a duration of anesthesia of