YELLOW FEVER. 105 



yellow fever in unusual places by vessels which came 

 from its ordinary habitat. 



On the other hand, physicians very generally reject the 

 doctrine of its contagiousness, because it is not carried 

 about by infected persons, because its victims, however 

 much crowded together in a hospital which is removed to 

 a short distance from the infected spot, do not produce it 

 in those who visit or nurse them, or sleep with them at 

 night. Persons thus habitually exposed, show their sus- 

 ceptibility, by suffering an attack by visiting, even for a 

 few minutes, only the open streets of the morbific place. 

 This objection is so strong as to throw the contagionists 

 into all kinds of devices to defend their untenable position; 

 such as, conditional contagion, contingent contagion, con- 

 current local causes, tertium quids, between the imported 

 and local agents, all of which, entirely hypothetical, de- 

 pend for existence, even in the minds of their expounders, 

 upon the first assumption, the contagion of yellow fever ;^ 

 an assumption which owes its acceptability solely to the \ 

 fact of importation in ships, and propagation by fomites, 

 together with the hitherto insuperable difficulty of giving 

 to it a different explanation. " There is our position !' 

 say they to their opponents; " destroy it if you can!" 

 The opponents are reduced to the necessity of giving to 

 numerous well attested phenomena a flat denial. The 

 anti-contagionists, on the other hand, point to the dispers- 

 ing invalids of a pestilential city, and ask, why they carry 

 not disease to the country. They exult in the immunity 

 of the hospitals, and, in their turn, inquire with confidence, 

 " Where is your contagion?" They are answered by sub- 

 tleties, and suppositions, and hypotheses. Is not all this 

 very contrary to the true spirit of philosophy ? Would it 

 not be better to admit that yellow fever is often imported 



