FEVER ' l.KS. 533 



chilliness with heat and Hushing, followed l,y \>- gradual wasting of 



the body, accompanied l>y \<\ 



tent, there being a period of ivmixM.>u and a period ( 



and sometimes twice, in tin- l\v. nt y-four h 



Certain, fevers, such as measles, scarlet fever, small \x>\, typh'. .-, as Ws 



know, generally spoken of as i: Etaet, tliai r are 



i>elieyed to originate, through the infect ion of the system with certain poisonous 

 matters. The poisons which give rise to these diseases diller from ordinary 

 poisons chiefly in the fact that they ran reproduce themvlves under favourable 

 conditions to an endless degree. .For example, a child becomes infected \\ith 

 scarlet fever, this child can communicate (he disease to ten or more people, and 

 each of these to ten more in turn, and so on, so that from one child the fever 

 may spread to 10, 100, 1,000, or 10,000 people. We find ilustrati-- 



this fact in the devastating scourges which at different periods in the world's history 

 have spread over the surface of the globe. Infectious diseases have often destroyed 

 the army of the conqueror, and have been the means of removing whole races of 

 mankind from the earth. It is supposed by many students of ancient history 

 that the prevalence of infectious diseases played a prominent part in the pro- 

 duction of the fall of the might and civilisation of Greece and Rome. In former 

 times epidemics of fever appear to have raged with much greater vigour than those 

 which we nowadays are accustomed to witness. Thus we learn that in the middle 

 of the fourteenth century an epidemic of fever, which occurred in Venice, ca 

 off more than three-quarters of the inhabitants, and that the : >aped 



death only by flying to the islands. It is said that during the same epidemic more 

 than a million lives fell a prey to the disease in Germany alone, and tl. 

 Italy scarcely the half of the inhabitants were left. Even at the present day the 

 mortality from fevers is something enormous. It has been calculated that all the 

 other mighty casualties of nature, such as earthquakes, volcanic eruptions, mountain 

 avalanches, hurricanes, and inundations by sea, have never, in the whole of the 

 world's history, destroyed even approximately half as many lives as a s 

 ordinarily extensive epidemic. Even in our most sanguinary wars the devastation 

 caused by the scientific instruments of death has been trifling compared with the 

 mortality which has followed the outbreak of an epidemic of fever in the armies. 



The causes which have operated to modify the severity of modern epidemics are 

 well worthy of our best study and consideration. It is sometimes said that there 

 has been a change in the type of disease, but it is infinitely more prol>aMe that the 

 advance of civilisation, and the improved sanitary conditions under which we live, 

 have been the important factors. When we consider how little was done during 

 antiquity and the Middle Ages to stamp out disease and arrest the progn 

 pestilences, our only wonder is that the mortality, great as it was, was not con- 

 siderably greater. It is probable that people owed their protection rather to the 

 difficulties of travelling, and the slowness of communication, than to any efforts of 

 their own. 



It is now usually considered that most fevers are caused by the entrance of 

 some very minute organism into the system. This view, at all events, in a modified 



