E.. Frankland on the Source of Muscular Power. 395 
muscular exertion is really dependent upon muscular oxydation, 
we have to consider we should be the products, and what the 
value of this oxydati ... And again, page 108, “The 
slow oxydation of so muc mh carbon and hydrogen i in the human 
body, therefore, will —<— produce its due amount of heat, or 
force liberated by the stl of the st a and hydrogen of 
fat is expressed solely in the form of heat, the ‘combustion of - 
not the material by the chemical ge re which mi an igcohy work 
is produced.” He showed that the 15 lbs. of dry muscles of a 
man weighing 150 Ibs. would, if their mechanical work were 
due to their chemical change, be completely oxydized in eighty 
days, the heart itself in eight days, and the ventricles of the 
eart in two and a half days. After endeavoring to prove by 
physiological arguments that not one per cent of the oxygen ab- 
sorbed in the lungs could possibly come into contact with the 
substance of the muscles, Mayer says, ‘The fire-place in which 
this combustion goes on is the interior of the blood Vessels, the 
blood however—a slowly-burning liquid—is the oil in the r Pe 
of life. . . . Just as a plant-leaf transforms a given mechanical 
effect, light, into another force, chemical difference, so does the 
motion two aie are necessary—the conveyance of combusti- 
ble, substances to the muscle by the blood, and the access of 
oxygen by respiration. He concluded that the chief combusti- 
ble substance so used was fat. A century before —— iso- 
lated oxygen, ‘Mayow-m was aware of its existence in the air, in 
nitre, and jn nitric acid; he knew that ieabation: is supported 
by the oxygen of the air, and that this gas is absorbed in in the 
ween organische Bewegung in ihrem Zusammenhange mit dem Stoffwechsel,” 
* ‘De Motu musculari, 1681. Mayow was born in 1645, and died 1679, 
