FUSION OF CARDIAC ANLAGES IN THE CAT 



57 



freely-treated model of the heart of a human embryo of 7 to 8 

 pairs of somites. In both there is a bulbo-ventricular cleft on 

 the left and there is little in this view of either model to suggest 

 a mode of formation of the loop different from that given by 

 jNIall, which is simply the deepening of this sulcus between bulb 



Fig. 7 The same model as in figure 6 viewed somewhat from the right and 

 above. 1, Bulbus; 2, shoulder of left mantle; 3, shoulder of right mantle; 4, 

 bulbo-ventricular sulcus ; 5, right bulbo-ventricular sulcus ; 6, right lateral meso- 

 cardium. 



and ventricle. The heart of the cat is rather more plump, its 

 contour more convex, but this may well be due to a greater dis- 

 tension with blood. Two details small in size but not in mor- 

 phologic significance are present in the cat, which are not shown 

 in the figure of the human heart. The right margin has a small 

 indentation which is the remnant of the right bulbo-ventrical 



