Page:Popular Science Monthly Volume 6.djvu/726

706 do?" The answer was, "Diminish the tension on the blood-vessels, and there need be no fear of tearing them in a weak place." Now, this expresses in plain terms the exact cause of apoplexy in the great majority of instances; and it is one, too, which every one has it in his power to prevent. A blood-vessel of the brain, from causes which will presently be mentioned, has lost some of its elastic strength; food is abundant, digestion is good; blood is made in abundance, but little is worked off by exercise; the tension on every artery and vein is at a maximum rate; the even, circuitous flow is temporarily impeded at some point, throwing a dangerous pressure on another; the vessel which has lost its elastic strength gives way, blood is poured out, a clot is formed, which, by its pressure on the brain, produces complete unconsciousness. This is the apoplectic stroke. It will be perceived that there are two leading conditions upon which the production of the stroke depends: a lessened strength in the vessel, and an increased tension on it.

There are no vessels carrying blood to and from the various organs of the body which so frequently rupture as those in the brain. The causes that produce this result are the fatty degeneracy of the middle arterial coat of the cerebral vessels, whereby their elastic strength is much impaired, the great irregularity of blood distribution to the contents of the cranium, and the little support which the pulpy substance of the brain gives to the weakened vessels embedded in it.

The forms of degeneracy that are found in the arteries of the brain are the fatty and the calcareous. The microscope has made some startling revelations on this fatty decay. The strong, elastic fibres, that should make up the substance of the middle arterial coat, are, in places here and there, no longer to be seen, their place being occupied by fatty globules, which have very little resisting power to a disturbing force.

The chief causes which produce this structural change are the habitual use of ardent spirits and tobacco. Every one is aware that the leading effects of these agents on the body are such as show that the functions of the nervous system are more affected than any other; and the physician also knows that, when symptoms of disorder arise from their use, they are such as denote that the nervous system is almost alone implicated. Delirium tremens, insomnia, tremulous hands, and nervous headaches, are some of the characteristic effects of the habitual use of stimulants and narcotics.

Ardent spirits also tend to produce an over-fullness of the cerebral vessels, and to affect the functions of the brain in a manner which strangely blends stupidity, brightness, and exhilaration. Effects so unnatural, and so frequently ending in disease, influence injuriously the nutrition of the nervous centres. And to interfere with the nutrition of any part of the body is simply to impair the life and power of its structure. The evidences of this impairment may not be felt