MALFORMATIONS OF THE BULBUS CORDIS 17 



modifications:— (i) The adjacent sides of the bulbus and ventricle fuse 

 and rapidly disappear, and thus the bulbus comes to open freely into the 

 right ventricle (see figure 9, A, B) ; (2) the lesser curvature is represented 

 by only the base of the mitral valve (see fig. 9, B, 9) ; (3) the lower or 

 ventricular orifice of the bulbus is carried up to the base of the anterior 

 cusp of the mitral valve ; (4) the upper or aortic orifice of the bulbus 

 becomes applied to the base of the anterior cusp of the mitral. Further, 

 it is to be noted that the aorta arises from the part of the bulbus which 

 undergoes atrophy in the disappearance of the lesser curvature of the 

 heart (see figure 9, B, f). It is in this manner that the part of the 

 bulbus corresponding to the origin of the aorta becomes stretched and 

 disappears, while the part of the bulbus which remains, representing 

 almost the entire bulbus, becomes incorporated in the right ventricle. 

 Thus it comes about that the part of the bulbus cordis corresponding 

 to the origin of the aorta disappears completely at a very early date, and 

 usually not a trace of it is to be seen at the aortic opening of the left 

 ventricle. Occasionally remnants do occur ; all the cases showing such a 

 condition which I have had an opportunity of examining have been 

 regarded as malformed by the cicatrical effect of endocarditis, but a 

 closer examination of the condition, and a fuller understanding of the 

 development of the heart, show that such an interpretation is untenable. 

 In figure 10 is given a representation of the heart of a man, aged 20, who 

 died recently in the London Hospital. It shows a condition which I 

 interpret as being due to the persistence of the bulbus cordis 

 round the orifice of the aorta from the left ventricle. From 

 figure 9, B, it will be seen that such a remnant should form an 

 endocardial ring round the aortic orifice (the area derived from 

 the bulbus is stippled in figure 9, B). The case is one in 

 which there was an acute infection of both mitral and aortic valves, 

 with ulceration and formation of vegetations. But the stout fibrous 

 ring which surrounds the orifice of the aorta, below the aortic cusps, and 

 is continuous with the fibrous tissue of the heart from which the aorta 

 arises, could not be produced by any lesion which is known to occur in 

 acute or chronic endocarditis. On the mitral valve, the ring is represented 

 by endocardial elevations which, in section, are seen to be made up of, 

 not inflammatory tissue, but of one closely resembling Whartonian jelly, 

 a tissue in which branched cells are embedded in a jelly-like ground 



(71) 



