Reviews

The Healing Power of Nature

This book, by a distinguished physiologist, should be read by every layman who wishes to understand the fundamentals on :which must. be based all sound medicine and all sound hygienic practice. It explains, in language free from technical jargon, what is known of the way in which our bodies preserve . their stability in the midst of an everehanging environment ; and of the forces within us constantly .tending to the main- tenance of equilibrium and harmony among our several . parts—in other words to the preservatinn of health.

The instability of the units of which our bodies arc com- posed is extreme. As Professor Cannon reminds us, the minute pulses of energy that course along our nerves to our muscles find there a substance -so delicately sensitive to slight disturbance that, like an explosiVe- touched off by a fuse, it may discharge in-'a 'powerful movement." The sensory surface in the nose is affected by one part of vanillin in ten million parts of air ; and the eye is sensitive to .an amount of energy which is one two-thousandth of that required to affect the most rapid photographic plate. These examples of the instability of our-bodily parts btit bring into stronger relief the potency of the mechanism which yet succeeds in maintaining the whole in a state not far removed front

uniformity : - - " Men may be exposed to dry heat at temperatures of- front

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temperature above normal ; whilst arctic mammals, when exposed to cold as low as 31 degrees below zero, Fahrenheit, do not manifest any noteworthy fall of body temperature."

So, again, with the heat produced within us by severe muscular effort ; which, were it not promptly dissipated, would, in twenty minutes, coagulate the albuminous substances of the body like a hard-boiled egg. These, and a hundred similar self-regulatory • phenomena, confirm and amplify

the shrewd inference of Hippocrates that disease, when cured at all, is cured by the ids medial:1.LT naturae.

We commonly think of ourselves as terrestrial animals, but this is a conclusion that needs considerable qualification. Every one of the millions of living cells which make up our bodily substance is essentially as much a water animal as is the unicellular amoeba- itself. The entire surface which

we present to the air consists of a covering of dead material, within which all of us that is vital has its being. ." Ea& cell has needs similar to those of the single-celled creatures that live in the flowing stream " ; but the cells of our .body are shut away from any chances to obtain directly food and oxygen from the distant larger environment, or to dis- charge into it the waste materials which result from activity." Instead, we are furnished with an elaborate-system of moving streams within the body itself ; and with one or other branch or tributary of these each of the cells of which we are com- posed is in direct contact. The ingenious means whereby this fluid matrix is kept constant in its composition, and is distributed according to the local needs of the moment, are described by Professor Cannon in two of the most interesting chapters of his book.

There seems, indeed, no end to the tale of subtle and intricate defensive mechanisms utilized without our . con- sciousness by the several tissues of the body. But for these clearly purposive reactions, it would be impossible for us to live for a week amid the infinity of potential dangers and destructive forces which share with beneficence the realm of nature. Moreover, line after line of defence is available should external circumstances prove too powerful for what may be called the police forces of the body. Take, for example, the arrangements already mentioned, those which limit the shifting of the body temperature in one direction or another :

" If dilation of the skin vessels does not stop the rise of body temperature, sweating and even panting intervene. If conservation of heat by constriction of the skin vessels does not prevent a fall of temperature, there is a chemical stimulation of more rapid burn- ing in the body by means of secreted adrenin ; and, if that in turn is not adequate to protect the internal environment from cooling, greater heat production by shivering is resorted to."

But, apart from these emergency measures, there are other routine defences spontaneously organized to balance seasonal climatic variations. Such is the luxurious growth, at the approach of winter, of hair, fur or feathers in animals so clothed. Even more complex are the automatic defences of our living cells against the attacks of our hereditary foes, the bacteria—the escape of plasma into the invaded tissues and the formation of a fibrinous entanglement, the closing of the local lymph vessels by clots, the gathering of leucocytes

which then, within the area securely cut off from the rest of the body, carry on battle to the death, involving themselves together with their enemies and the local tissues in destruction, but preserving our whole organism from infection and possible

disaster. Nor is this the whole story ; for, should the bac- teria slip through the encircling entanglements, or manu- facture poisons which penetrate the defences, a further protective technique is available. Neutralizing anti-toxins are manufactured, and the presence of even a few bacteria in the general blood stream leads to the prompt synthesis of chemical products which first drive the bacteria into heaps and then destroy them.

It is our increasing knowledge of these automatic healing efforts of Nature that forms the basis of that scientific medicine which is as yet at a rudimentary stage of development. Only ignorance and childish conceit can account for the sneers and cavillings which superior persons often cast at the tentative efforts of imaginative science to co-operate with these spon- taneous activities of our unconscious selves. The instances quoted are but a few among the many that are simply and clearly explained in this admirable book.

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