14 



QUATERCENTENARY STUDIES IN PATHOLOGY 



which represents the bulbus cordis. The aortic part of the bulbus 

 atrophies and disappears, and in order to understand this alteration, I 

 propose now to describe briefly the metamorphic changes which, thanks 

 to the labours of His, are known to occur in the human heart during the 

 third and fourth weeks of development. The condition of the human 

 heart during the fourth week is shown in figure 7 ; A represents the 

 condition about the beginning of that week, and B a stage towards the 

 end of the same week. Both are taken from illustrations given by His. 



A 



Figure 7, A, heart of a human embryo, 4*5 mm. long. (His). 

 B, heart of an "i 5 " long- (His). 



Primitive aortic stem from which pulmonary artery and aorta will be developed. 

 Bulbus cordis. 



Upper or aortic orifice of bulbus cordis. 

 Lower or ventricular orifice of bulbus cordis. 

 Ventricle. 



Auricular canal (auriculo-ventricular junction). 

 Left auricle. 

 Right auricle. 



(I) 

 (2) 

 (3) 

 (4) 

 (5) 

 (6) 

 (7) 

 (8) 



To assist in the interpretation of these hearts, I give a figure of a fish's 

 heart (Echinorhinus spinosus) drawn from the same point of view — in 

 each case the sternal aspect of the heart is represented. In their shape 

 the ventricle and bulbus of the fish's heart recalls the stomach ; the 

 auricular canal (6) corresponds to the oesophagus; the auriculo-ventricular 

 junction, the oesophageal orifice, the ventricle, the cardiac part of the 



(68) 



