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add that his great knowledge of the pathology of the heart is fully 

 equalled by the kindness with which he places that knowledge at the 

 disposal of the humblest searcher after truth. Jealousy is so often the 

 characteristic of scientific men, that it is pleasant to meet a man who is 

 entirely free from it. I suppose that this quality of jealousy which men 

 of science possess entitles them to be considered as rising to the level of 

 the better and the gentler sex. In the first place, each of these fibres 

 is so arranged that it is capable of contracting to eight-ninths of its 

 length, because I find that each of these fibres is the same length : the 

 length of the common fibres is the same, and the length of each group 

 of proper fibres is the same, but of course the two groups differ from 

 each other in length. Now, since each of these fibres is so arranged 

 spirally and is of the same length, and is capable of contracting to its 

 full extent when ordered to do so by the brain, you will see that, as far 

 as they are concerned, the principle of least action has been fulfilled. 

 But there is a remarkable opportunity of applying to this case a crucial 

 test of whether the principle of least action is or is not the great prin- 

 ciple in muscular mechanics that I assert it to be. I have two groups 

 of fibres, one surrounding the two cavities and another group of fibres 

 surrounding one cavity, and by the application of a little geometri cal 

 manipulation I was able to arrive at a very remarkable result. 



If I call L the length of one of these spiral fibres going round the 

 entire heart, the volume of the whole heart will be proportional to the 

 cube of L, which being a linear symmetrical dimension, the volume of 

 the whole heart will be proportional to its cube ; so that — l'^ will be 

 proportional to the difference in the volumes of the heart before and 

 after contraction. But the difference in the volumes of the heart before 

 and after contraction is the sum of the volumes of the two cavities. 



I will call A and p the left and right ventricles. If we take the fibres 

 that go round a single cavity, I find that if / and /' represent their 

 lengths before and after contraciion, that in like manner P — /'^ virill be 

 proportional to the volume of the left ventricle. 



Therefore, if the principle of least action be true, I can predict a 

 thing that at first sight appears very strange. I can find the ratio 

 which the volumes of the two cavities bear to each other by the 

 measurement of the lengths of the fibres that surround them. On 

 measuring these fibres it comes simply to this. Let L be the length of 

 the fibres that go round the entire heart ; let / be the length of the 

 fibres that go round the left ventricle. Find those lengths and cube 

 them. The ratio of those cubes will be proportional to the sum of the 

 right and left ventricles divided by the left. There are theoretical 

 grounds which I believe are almost of themselves sufficient to entitle 

 us to believe that these two cavities are of equal volume, and there- 

 fore that this fraction will come out equal to 2. I have taken, how- 



