DEVELOPMENT OF THE HUMAN HEART 



285 



terior cusps of the tricuspid valves. Kent 34 found such bundles 

 in the left wall of the heart as well as in the right wall in young 

 rats and young rabbits. It is possible that some of these strips 





A.F, 



m 



I Y 



\ If 



22 



Fig. 22 Sagittal section. Embryo 18.5 mm. long (No. 431). X 40. 

 Fig. 23 Sagittal section. Embryo 20 mm. long (No. 368). X 40. 



may be constant or they may be variations. At any rate their 

 presence has not been established as has been the atrio-ventricular 

 muscle of His. 



34 Kent, Researches on the development of the mammalian heart. Journal of 

 Physiology, vol. 14, 1893. 



