436 FKAGMENTS OF SCIENCE. 



that labourer's work exerted on the muscles alone, they 

 would be utterly consumed in 80 days. The heart 

 furnishes a still more striking example. Were the 

 oxidation necessary to sustain the heart's action exerted 

 upon its own tissue, it would be utterly consumed in 8 

 days. And if we confine our attention to the two 

 ventricles, their action would be sufficient to consume 

 the associated muscular tissue in 3J days. Here, in his 

 own words, emphasised in his own way, is Mayer's 

 pregnant conclusion from these calculations: 'The 

 muscle is only the apparatus by means of which the 

 conversion of the force is effected ; but it is not the 

 substance consumed in the production of the mecha- 

 nical effect.' He calls the blood ' the oil of the lamp of 

 life;' it is the slow-burning fluid whose chemical force, 

 in the furnace of the capillaries, is sacrificed to produce 

 animal motion. This was Mayer's conclusion twenty-six 

 years ago. It was in complete opposition to the scien- 

 tific conclusions of his time ; but eminent investigators 

 have since amply verified it. 



Thus, in baldest outline, I have sought to give some 

 notion of the first half of this marvellous essay. The 

 second half is so exclusively physiological that I do not 

 wish to meddle with it. I will only add the illustration 

 employed by Mayer to explain the action of the nerves 

 upon the muscles. As an engineer, by the motion of his 

 finger in opening a valve or loosing a detent, can liberate 

 an amount of mechanical motion almost infinite com- 

 pared with its exciting cause, so the nerves, acting upon 

 the muscles, can unlock an amount of activity, wholly 

 out of proportion to the work done by the nerves them- 

 selves. 



As regards these questions of weightiest import to the 

 science of physiology, Dr. Mayer, in ] 845, was assuredly 

 far in advance of all living men. 



