8 



QUATERCENTENARY STUDIES IN PATHOLOGY 



the musculature of the auricle replaces a great part of that of the sinus 

 venosus. The submergence of the bulbus evidently constitutes a critical 

 phase in the developmental metamorphosis of the heart, and it is during 

 the critical phase that malformations are apt to occur and give rise to 

 the various lesions I shall now proceed to describe. 



Figure 3, heart of a man aged 20 who died, after two months' illness, from an acute 

 infection with endocarditis. 



(i) Pulmonary artery. 



(2) Aorta. 



(4) (5) Fibro-muscular contriction marking the lower infundibular or bulbar orifice. 



(6) Body of right ventricle. 



(7) Tricuspid valve. 



(8) Left ventricle. 



(9) Right auricle. 



(A) Right septal band. 



(B) Left septal band. 



Between A and B is seen a wide infundibular raphe. 

 Between 4 and 5 is seen a small interventricular foramen. 



The first class of cases I wish to deal with is that described as 

 division of the right ventricle ; they are really cases in which the 



(62) 



