7 o6 THE POPULAR SCIENCE MONTHLY. 



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 sub- 

 stance 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 nutri- 

 tion 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 im- 



