the animal’s body with the quantity it needs. As Cannon points out,
the liver is the busiest and most versatile of all body organs. Yet three
fourths of the liver can be lost without causing any serious interference
with the important functions it performs.

The digestive system also has a wide margin of safety. Most of the
stomach can be removed without greatly impairing digestion and nutri-
tion. Some people have lost as many as 10 feet of small intestine without
serious results, and a large part of the large intestine can be cleared away
with impunity. Another factor of safety in the alimentary canal is
the provision of enzymes at various stages along the route which can
duplicate one another’s work.

Many more instances might be given to prove that our bodies are
constructed with a wide margin of safety. Perhaps the best proof is that
we ourselves, without being consciously aware of it, conduct our lives on
the assumption that our bodies are run according to an economy of
abundance rather than an economy of scarcity. Not until we are forced
to economize on bodily strength, not until we lose several feet of intestine
or a kidney or a lung, do we realize that we have been endowed by
Nature with more than enough rather than just enough to live on.

Here the old adage “willful waste makes woeful want” may be in-
serted as a warning. Factors of safety are for unlooked-for contingencies.
By and large we get along much better if we have all our parts in place
and working properly. It is not wise to spend reserves recklessly or to
invest them in risky ventures simply because we have them. It is a very
comfortable feeling to know they are there in a safe place ready to be
drawn on when the need arises. Thus, the fact that our bodies are con-
structed on an extravagant scale is no reason for sacrificing our reserves
to ambition, carelessness, ignorance, preventable infection, or whatever
else exacts the tribute that leads toward untimely death.

It is highly encouraging to note that immunization procedures, improved methods of
diagnosis, and other measures for controlling disease in childhood are making it possible
for many more people to grow up with their margins of safety undepleted. Thus we are
coming closer to that hope, so beautifully expressed by Dr. Lee K. Frankel, “‘of growing
old gracefully, in the possession of our mental and physical powers, so that whatever the
biologic age, whether the present one or whether through the efforts of science it may be
extended, the final breakup will come as came that of the deacon’s one-horse shay. A
century of unimpaired usefulness and then dissolution, with springs and axles and hubs
and tires going to pieces all at once. When we can approximate this happy state, we
shall understand what another great American poet meant when he asked us to meet
the great finale ‘like one who wraps the drapery of his couch about him, and lies down

to pleasant dreams.’ ”
REFERENCES

Warer B. Cannon. The Wisdom of the Body. W.W. Norton & Company, New York. 1939. Chapter XV.

The Harvey Lectures, 1906-07. J. B: Lippincott Company, Philadelphia, 1908. “The Factors of Safety in
Animal Structure and Animal Economy,” S. J. Metrzer. Pages 139-169.

ScHooL HeattuH BurEAU—WELFARE DIvIsIoNn

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