Action Potential Studies of Afferent Fibres in the IXth and Xth Cranial Nerves of the Frog

The carotid bifurcation and carotid gland are the site of origin of stretch receptor fibres which join the glossopharyngeal nerve. These fibres behave in a manner similar to those of the carotid sinus nerve of mammals, as shown by their impulse activity under conditions of arterial distension. The pulmo‐cutaneous trunk possesses stretch receptor fibres which join the laryngeal branch of the vagus. The possible function of these fibres is discussed. The pulmonary branch of the vagus contains fibres which originate from stretch receptors in the lung tissue. Inflation of the lung causes an increasing discharge of such fibres. It is suggested that the development of this mechanism is related to the mode of respiration displayed by the frog.