106 YELLOW FEVER. 



in ships, is now and then carried in trunks, and may pos- 

 sibly be sometimes an accident of the locality ? Might it 

 not be also said, that we know of no contagious disease 

 which presents any analogy to the contingent contagion 

 claimed for yellow fever, and that, therefore, we must, for 

 the present, suppose that it is portable and yet is not con- 

 tagious ? 



If I have made a good footing for the fungi, as pro- 

 ducers of diseases very like to yellow fever, I may be in- 

 dulged in my hypothesis, which alleges, that a tropical 

 fungus, carried off in dark, damp, animalized holds of ships, 

 or in the offensive clothes of sick or dead seamen, may be 

 introduced into the summer-clime of unaccustomed places, 

 and there, as it came from, may go to, the shore, and 

 be sometimes reproductive. May I not suppose that 

 the germs, when once ashore, may slowly migrate land- 

 wards, and even by chance be carried or wafted to other 

 neighboring spots, where they may grow, and create new 

 foci of disease? that the requirements of an exotic may 

 make such visitations rare, and such dispersions unusual? 

 and that the equatorial plants may be nipped, and even 

 totally destroyed by an unaccustomed frost ? 



Through this theory of ours, we can easily see why the 

 disease may be imported, why it is imported rarely, and 

 why it makes so slow a progress from the spot to which 

 originally brought. It will, also, explain its non-conta- 

 gious character, and even its occasional but rare visit to a 

 village or hamlet. It may also account for its apparently 

 spontaneous appearance in such places as Charleston, Sa- 

 vannah and New Orleans, in which the winter may not be 

 severe enough to kill the germs, but yet may so affect 

 them as to make their reaction difficult or partial. 



It is only thus that we can comprehend how a perfectly 



