240 POPULAR SCIENCE MONTHLY. 



ago. But, as a matter of fact, this parasite, which we now know is 

 present in the blood of those sick with the disease, has thus far eluded 

 all researches. Possibly it is ultra-microscopic. However this may be, 

 it is not the only infectious disease germ which remains to be discovered. 

 There is without doubt a living germ in vaccine lymph and in the virus 

 from smallpox pustules, but it has not been demonstrated by the micro- 

 scope. The same is true of foot and mouth disease and of infectious 

 pleuro-pneumonia of cattle, although we know that a living element of 

 some kind is present in the infectious material by which these diseases 

 are propagated. In Texas fever, of cattle, which is transmitted by in- 

 fected ticks, the parasite is ver}'- minute, but by proper staining methods 

 and a good microscope it may be detected in the interior of the red 

 blood corpuscles. Drs. Eeed and Carroll are at present engaged in a 

 search for the yellow fever germ in the blood and in the bodies of in- 

 fected mosquitoes. What success may attend their efforts remains to be 

 seen, but at all events the fundamental facts have been demonstrated 

 that this germ is present in the blood and that the disease is trans- 

 mitted by a certain species of mosquito — C. fasciatus. 



The proper measures of prophylaxis in view of this demonstration 

 are given in the following circular, which was submitted for my approval 

 by the Chief Surgeon, Department of Cuba, and has recently been pub- 

 lished by the Commanding General of that Department, who, until 

 quite recently, was a member of the Medical Corps of the Army : 



CiRCULAK, HeADQUARTEKS DEPARTMENT OF CtJBA, 



No. 5. Havana, Ajrril 21, 1901. 



Upon the recommendation of the Chief Surgeon of the Department, the fol- 

 lowing instructions are published and will be strictly enforced at all military 

 posts in this Department : 



The recent experiments made in Havana by the Medical Department of the 

 Army having proved that yellow fever, like malarial fever, is conveyed chiefly, 

 and probably exclusively, by the bite of infected mosquitoes, important changes 

 in the measures used for the prevention and treatment of this disease have be- 

 come necessary. 



1. In order to prevent the breeding of mosquitoes and protect ofGcers and 

 men against their bites, the provisions of General Orders No. 6, Department of 

 Cuba, December 21, 1900, shall be carefully carried out, especially during the 

 summer and fall. 



2. So far as yellow fever is concerned, infection of a room or building 

 simply means that it contains infected mosquitoes, that is, mosquitoes which 

 have fed on yellow-fever patients. Disinfection, therefore, means the employ- 

 ment of measures aimed at the destruction of these mosquitoes. The most effect- 

 ive of these measures is fumigation, either with sulphur, formaldehyde or in- 

 sect powder. The fumes of sulphur are the quickest and most effective insec- 

 ticide but are otherwise objectionable. Formaldehyde gas is quite effective if 

 the infected rooms are kept closed and sealed for two or three hours. The smoke 

 of insect powder has also been proved very useful; it readily stupefies mos- 

 quitoes, which drop to the floor and can then be easily destroyed. 



