Dr. Mac Culloch on Malaria on Ship-board, 53 



The contagious fever, or typhus, varies exceedingly in the 

 degree of severity ; and this is also true of marsh fever. And 

 while the term putrid fever has been applied to extreme cases 

 of the former, slighter fevers, supposed to belong to the same 

 species, have been popularly called low fever, and nervous 

 fever, and so forth ; while these terms have also been adopted 

 by physicians. Referring to the above-mentioned remarks on 

 the causes of fever, to what is here generally said on this 

 subject, and to all that physic really knows about fevers, or de- 

 termining not to follow the common lax language and reasoning 

 of this branch of science, but to limit myself to that which is 

 known and proved, such a low or nervous fever must belong to 

 one or other of these species ; namely, the contagious, or the 

 marsh fever, because physic cannot prove another species and 

 a third cause. 



Now it is true that a fever of this mild description can be 

 produced by contagion, and the proof is, that such instances 

 will occur, in an epidemic period, among severe cases ; while also 

 such a mild disease will propagate itself, and even produce a 

 severe case ; and while, further, the very cause may some- 

 times be traced, for such an individual instance, in the expo- 

 sure to a contagion. But I am very certain that if the very 

 great majority of such mild fevers were carefully examined, 

 they would be found to appertain to the marsh fever ; while 

 the error here is only a part of that general error of which I 

 have been treating. And, but for this standing and almost 

 universal error, physicians ought to have perceived this long 

 ago, and might ascertain it every day. They should have 

 believed it always, and ought to believe it now, because they 

 can trace no contagion whence these fevers could have arisen, 

 and because they are dispersed cases occurring everywhere, 

 and without the existence of any epidemic to which they 

 could belong. If it does happen that many occur in one 

 neighbourhood, or even, perhaps, in one house, thus giving 

 the false impression of an epidemic and a contagion, I have 

 already shown how this is the consequence of exposure to a 

 common cause. 



But there are other circumstances indicating the same thing. 

 There can be no fever without a cause ; there are but two 



