42 -Dr. Mac Culloch on Malaria on Ship-board. 



and as destructive ; but the essential distinction always con-* 

 tinues. These cannot be communicated from one individual 

 to another. 



Thus simply stated, it might be supposed by general readers 

 that nothing could be more easy than to make the distinction 

 in practice. Yet the fact has proved far otherwise, and even 

 in much graver cases than the fevers of our own country, or 

 even the fevers of ships ; from causes, some of which I must 

 allow my own profession to assign, as they would scarcely 

 thank me for the attempt. To these readers, however, it will 

 be interesting to know that on this have been founded all the 

 confusion and all the disputes which so long occupied the 

 world, and still occupy it occasionally, respecting the yellow 

 fevers of the West Indies and of America, the fevers of 

 Gibraltar and Cadiz, and the more recent ones of Barcelona and 

 Alicante : while the confusion, the inconveniences, and the 

 terrific mortalities which have resulted from these errors, I 

 could not here undertake to speak of, without trespassing on at 

 least the bounds of this essay, if not so very much upon its 

 objects. Generally, however, I may venture to say, that as 

 severe typhus and severe marsh fevers often put on the same 

 aspect, so while the peculiar biliary affections caused by heat 

 are common or general in hot climates, it has happened that 

 these, occurring in each kind or class of fever, and forming an 

 obvious symptom, as also giving rise to a popular term, have 

 caused the name Yellow Fever to be applied indiscriminately 

 to both. Thus there has been a yellow fever which was con- 

 tagious, and a yellow fever which was not contagious, or a 

 marsh fever ; this last being the common endemic of the West 

 Indies and other tropical climates, as of Spain, while the former 

 has been a contagious disease, casually arising, or imported in 

 ships, and propagated in the usual manner. That the yellow 

 fever and the mortal fever of Gibraltar proved of this 

 nature, and that, in the last case in particular, this contagious 

 '^ yellow" fever had been mistaken for the non-contagious, or 

 marsh " yellow" fever, with mortal consequences of the most 

 tremendous amount, will form a sufficient illustration to ordi- 

 nary readers, as to this particular error ; while it will be a suffi- 

 cient example also of the exactly reverse error, that the fever 



