394 LE. Frankland on the Source of Muscular Power. 
ation of the food, and the mechanical work to the oxydation of 
the muscles. 
This doctrine, first promulgated, the speaker believed, by 
Liebig, occupies a prominent position in that philosopher's justly 
celebrated ‘Chemico-Physiological Essays.’ 
In his work entitled ‘ Die organische Chemie in ihrer Anwen- 
dung auf Physiologie und Pathologie, Braunschweig, 1842,’ Lie- 
big says, ‘ All experience teaches that there is only one source 
of mechanical power in the organism, and this source is the 
transformation of the living parts of the body into lifeless com- 
pounds.... This transformation occurs in consequence of the 
combination of oxygen with the substance of the living parts of 
e body.” And again, in his ‘Letters on Chemistry, 1851,’ 
p. 866, referring to these living parts of the body, he says, ‘“ All 
these organized tissues, all the parts which in any way manifest 
force in the body are derived from the albumen of the blood; 
all the albumen of the blood is derived from the plastic or san- 
—- constituents of the food, whether ‘animal or vegetable. 
t is clear, therefore, that the plastic constituents of food, the 
ultimate source of which is the vegetable kingdom, are the con- 
ditions essential to all production or manifestation of force, to 
all these effects which the animal organism produces by means 
of its organs of sense, thought, and motion.” And again, at 
page 374, he says, “The sulphurized and nitrogenous constitu- 
ents of food determine the continuance of the manifestations of 
force; the non-nitrogenous serve to produce heat. The former 
are the builders of organs and organized structures, and the pro- 
ducers of force; the latter support the respiratory process, they 
are materials for respiration.”’ ; 
This doctrine has since been treated as an almost self-evident 
truth in most physiological text-books; it has been quite recently 
supported by Ranke ;’ and, in his lecture ‘On the Food of Man 
in relation to his Useful Work, 1865,’ Playfair says, page 37, 
“ From the considerations which have preceded, we consider 
Liebig amply justified in viewing the non-nitrogenous portions 
of food as mere heat-givers. .. . While we have. been led to 
the conclusion that the transformation of the tissues is the source 
of dynamical power in the animal.” At page 30 he also says, 
“T agree with Draper and others in ssi fo the contrac- 
tion of a muscle due to a disintegration of its particles, and its 
relaxation to their restoration... . All these facts prove that 
transformation of the muscle through the agency of oxygen 38 
the condition’ of muscular action.” Finally, in a masterly Te 
view of the present relations of chemistry to animal life, pub- 
lished in March last,* Odling says, page 98, “ Seeing, then, that 
* «Tetanus eine Physi i Studie’ Leipzi 1865. 
saan ciate St tert 
