REPAIR IN EVOLUTION 77 



To interpret such an origin and their present functions it 

 seems they must be looked on as reaction products found 

 useful when the chambers of the heart arose as dilatations 

 of the primitive tube. Such dilatations were probably, 

 I would even say certainly, failures of the walls. The 

 incomplete pathological disaster of a repaired aneurism 

 helps us to understand such evolutionary failure and repair 

 as enabled the evolving heart to endure greater stresses, 

 and be once more repaired. It may be added that the 

 sponge-work of the evolving primary ventricle is strictly 

 analogous to the vascular spongy tissues seen in the male 

 organ. Every pathologist will admit that such a structure 

 may be logically compared with a vascular aneurism. 

 The path laid down by pathology is trodden by physiology. 

 It follows that during evolution there must have been an 

 immense destruction of organisms whose circulating canals 

 did not react, and numbers which retained their unaltered 

 " specific " characters. The same process goes on to-day. 

 Though many die of cardiac disease, it may be that much 

 youthful functional trouble, and even more serious adult 

 disorders, are even now re-moulding the heart. No organ 

 is perfect ; if it does not degenerate it progresses. Though 

 such processes are "disease," it by no means follows that 

 they will be destructive, any more than that the functional 

 incapacity of the tricuspid valves in athletes, which 

 probably precedes what is known as " second wind," is 

 anything now but a cardiac safety-valve. 



As we learn more of the heart and its latent capacities 

 we may, perhaps, say with the late Dr. H. G. Sutton, " we 

 trust nature too little, to say the least of it. " But there are, 

 of course, great difficulties to overcome before we can hope 

 to understand how the cardiac musculature has altered, 

 and may still be changing by the addition of new fibres. 



