BODILY WORK AND WASTE. 
155 
organism. Hence every organized structure is, as it were, a 
reservoir of force. The force which the plant receives from 
the solar heat is stored up in its cells, to be dispersed again 
gradually to the atmosphere in the shape of heat when it 
decays, or rapidly, when it burns as coal ; or, if consumed by 
an animal as food, is incorporated, with the elements of the 
plant, into the tissues of the animal which consumes it. These 
animal tissues thus become storehouses of power, which, as 
they waste and decay, is given off in the various forms which 
their peculiar character adapts them to eliminate. Thus the 
nervous tissues give it off as nerve-force ; the muscles, as motor 
force ; the fatty elements of the body, as heat; and so on. One 
of the most interesting branches of Dr. Haughton’s researches 
is the determination of the amount of force which is stored up 
in human muscles.* By a series of careful observations and 
calculations, he finds that the muscles which sustain the arm 
in a horizontal position — the central portion of the deltoid and 
the supraspinatus — weigh 5J ounces, or 2,242J grains, and 
that the work which they do in sustaining the arm until it 
becomes exhausted is equivalent to lifting half a ton through 
one foot. Hence it follows, that 1 lb. of such muscle con- 
tains, stored up in it, sufficient force to raise 1*56 ton through 
the same distance. This statement will go far to explain the 
origin of a portion, at least, of the force which is expended 
daily by the body of a living man. When it is remembered 
that during his waking hours the voluntary muscles of man 
are rarely at rest for more than a few seconds together, it will 
be seen that we have, in their constant waste alone, a fertile 
source for the evolution of force. But it is to the action of 
the involuntary muscles that we must look for the most abun- 
dant origin of the force which he is ceaselessly eliminating, 
and more especially to that most important of all the invo- 
luntary muscles, the heart, which, from the time he draws 
his first breath till his eyelids close in death, is never at rest. 
Most persons are aware that the heart is simply a muscular 
bag, divided into four cavities, and that the circulation of the 
blood through the blood-vessels, which is so essential to the 
maintenance of life, is mainly due to the force with which the 
muscular walls of the heart contract on the blood as it passes 
through these cavities. Few, however, would imagine the 
force which this small fleshy bag — no larger than one’s double 
fist, and only weighing about nine ounces — exerts on the mass of 
blood which it is called on to propel. Dr. Haughton has most 
ingeniously estimated that the force which the heart expends 
in the twenty-four hours is equivalent to lifting 124 tons one 
* “ Outlines of a New Theory of Muscular Action,” 1863. 
