Some Aspects of Heart Function in Patella vulgata L.

Abstract

WITHIN the pericardium of Patella vulgata L., in addition to the auricle and ventricle, there is a third chamber of the heart, the bulbus aortae or pseudo-chamber (Fig. 1, Ba). This chamber is situated laterally to the ventricle (V) and all blood leaving the ventricle passes through a valve into the bulbus aortae before leaving the pericardium by the anterior or posterior aorta (Aa and Pa). The function of the bulbus aortae is of considerable doubt, for although it is histologically indistinguishable from the ventricle it has not previously been observed to contract rhythmically. Wegmann¹ considered the bulbus aortae to be a sub-division of the ventricle, but all later workers argue that it is the fused, swollen bases of the anterior and posterior aortae².