INSECTS AND DISEASE. 655 



The same thing has been observed by Maceulloch in the Roman 

 Campagna, where, he says (p. 124), it is remarked that, " if the laborers 

 cut down certain plants (a bushy thistle chiefly), a fever, that would 

 otherwise not have occurred, is the consequence." 



In opposition to the mosquital origin of malarial disease it is known 

 that numerous mosquito wounds may be inflicted without the occur- 

 rence of malarial disease ; but this is by no means incompatible with 

 the theory. We do not yet know whether the poison be mosquital 

 saliva, or whether the fever-producing element be a bacillus with which 

 the puncturing proboscis of the insect may be loaded at the time of 

 inflicting its wounds. The scratch of a lancet will not produce vac- 

 cinia, unless the instrument be charged with vaccine matter ; the 

 puncture-needles of Pasteur would be harmless and impotent, did he 

 not load them with infecting bacteria ; so with dog-bites and hydro- 

 phobia, etc. 



Nay, it may even turn out that, under certain circumstances, mos- 

 quito-bites shall even be protective against malarial disease, for as 

 Pasteur and others are able to produce, artificially, " attenuated cul- 

 ture-fluids," the inoculation of which, while producing slight symptoms, 

 protects from more serious phases of disease, so may there exist in 

 nature naturally " attenuated " fever-poison fluids, the inoculation of 

 which, by mosquital puncture, may produce trivial symptoms, and thus 

 protect from more decided attacks of veritable fever. What product 

 of man's art has not been anticipated by Nature ? Hardly any. 



In the absence of direct experiments with the mosquito as a fever- 

 producing agent, I have endeavored to ascertain if the geographical 

 distribution of the insect had any relation with that of malarial dis- 

 ease. But the insect and the disease are both so wide-spread that it is 

 difficult to find any locality entirely exempt from either. Tasmania, 

 Singapore, New Zealand, Ceylon, and the Dismal Swamp of North 

 Carolina, as well as the bog-country of Ireland, are said by some 

 medical writers to be entirely exempt from fevers. Others discredit 

 this statement. I do not know who is right ; but I have endeavored 

 to ascertain whether insects of the mosquito tribe were or were not 

 rife in these localities. On this point there seems to be little sci- 

 entific knowledge available. Of the insects of Singapore a locality 

 in which the absence of fever seems to be generally admitted I have 

 been able to find no account. With relation to Tasmania (Yan Die- 

 men's Land), where exemption from fever is again generally admitted, 

 I have only been able to find, in the Capitol Library, one reference to 

 its insects. This is from the work of James Bischoff (London, 1832, 

 p. 33), who, quoting from Widowson's " Present State of Van Die- 

 men's Land," says : " The insects are not so numerous or so annoying 

 as in most other tropical countries. The ant, the mosquito, and a 

 common green fly are chiefly seen. The mosquito does not sting so 

 severely as in hotter climates." 



