INTERMITTENT FEVER. 673 



of others, where the water of other marshes was drunk without this 

 effect. If the morbific power were simply the product of chemical de- 

 composition, this exclusiveness would be entirely inexplicable. I have 

 no hesitation in saying decidedly that marsh miasm malaria must 

 consist of low vegetable organisms, whose development is chiefly due 

 to the putrefaction of vegetable substances. It is true these low 

 organisms have not actually been observed. No one has seen " mala- 

 ria spores," but the facts above mentioned, as well as many other 

 causes, urge us to believe that the poison exhaled by marshes, as well 

 as that given off by a patient with measles, is an organic living sub- 

 stance. There is, however, an important difference between the mias- 

 ma vivum, which is the specific cause of intermittent fever, and the 

 jontagium vivum by which the acute exanthemata, exanthematic ty- 

 phus, and other infectious diseases, spread. The latter reproduces 

 itself in organisms infected with it ; malaria, on the other hand, is not 

 reproduced in the body of a patient with intermittent fever. There is 

 no soil in the human body favorable to its development or increase. 

 Intermittent fever is never introduced into other places by patients 

 who have caught it in a swampy region. While a short residence in a 

 malarious district is often enough to give intermittent fever, one may 

 share the same ward with a large number of intermittent patients in a 

 hospital, at some distance from such a place, without danger. Hence, 

 in distinction to the " contagious " diseases, malarial fever is termed 

 " miasmatic contagious " or " purely miasmatic." 



There 'are extensive sections of country where the circumstances 

 for the formation of malaria exist everywhere, in all parts of which in- 

 termittent fever occurs ; but there are also small circumscribed mala- 

 rial foci, where numerous cases of intermittent are seen every spring 

 and summer, while the whole surrounding country remains free. In 

 these last-mentioned circumscribed malarial foci, in towns lying near 

 marshes, in certain sections or streets of cities, where intermittent fever 

 is endemic, some very interesting observations have been made about 

 the extension of malaria : among other things, it has been shown that, 

 from its point of origin, miasm spreads more readily in a horizontal 

 than in a vertical direction, it is often arrested by insignificant obsta 

 cles, such as groves, stone walls, etc., and rarely passes the boundaries 

 thus formed, unless the wind be in a particular direction. 



The extensive epidemics of intermittent fever which occasionally 

 appear are very remarkable. During such epidemics, while the cases 

 are unusually frequent in places where the disease is endemic, they 

 also occur in places where either no cases or only sporadic ones had 

 been seen for years. These epidemics do not always come in very 

 hot, moist seasons, so that they might be referred to the circumstances 



