1. Small animals (rat and guinea pig) vagotomized in the neck die within a period of hours, the lungs showing extensive congestion and edema.
2. Tracheotomy permits appreciably longer survival with minimal lung changes approximating those seen in the control animals.
3. Intrathoracic vagotomy (sparing the recurrent laryngeal nerve) on one side, and cervical vagotomy on the other, permits almost indefinite survival (guinea pig and rabbit), unless laryngeal paralysis from the unilateral denervation produces respiratory obstruction (rat, guinea pig, and rabbit).
4. Pulmonary edema following bilateral vagotomy probably results primarily from respiratory obstruction. It is suggested that circulatory failure may also be a factor of some importance. The rôle of vagotomy itself is considered in relationship to these two phenomena.
5. The reaction of smaller animals to bilateral vagotomy, with regard to lung changes, apparently differs in no way from that of the larger animals, but is less readily demonstrated because of the smaller diameters of the air passages.