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overlooked. The malarial germ has to pass through the body of cer- 
tain mosquitoes before attaining its highest development or its full 
life history. So far as we know as yet, certain mosquitoes are neces- 
sary secondary hosts in the development of this disease germ. The 
malarial germ is an animal organism. It belongs to the group of 
animals known as Protozoa, and from analogy it is altogether likely 
that the as yet undiscovered germ of yellow fever will also prove to 
belong to the same class of parasitic organisms. The parasite which 
causes Texas fever in cattle is also analogous to the minute spore 
which causes malaria in human beings. It inhabits the blood just as 
does the malarial parasite, and is conveyed by a biting insect; in this 
case the cattle tick, just as the former is conveyed by certain mosqui- 
toes. With diseases caused by bacterial organisms (which belong to 
the plant kingdom and not to the animal kingdom), a biting insect is 
not necessary for their transfer from a sick individual to a healthy 
one in the majority of cases, Such diseases are notably typhoid fever, 
cholera, and pulmonary consumption. With these diseases, and more 
especially the first two, the agency of non-biting flies as transmitters 
becomes important, and for this country their agency in the transfer 
of typhoid fever is especially important. It has been known for some 
time that flies may carry bacilli and bacteria on their feet. That was 
experimentally proven by allowing flies to walk over cultures, and 
after allowing them to walk upon sterilized media the same bacteria 
developed. Moreover, as early as 1888 it was shown by an Italian 
investigator that flies fed upon pure cultures of typhoid bacillus were 
able to transmit virulent bacilli with their excrement. Further early 
observations showed that flies are important agents in the transmission 
of Asiatic cholera. 
Typhoid fever was astonishingly prevalent in the concentration 
camps in this country at the outbreak of the war with Spain, and the 
disease received a thorough investigation at the hands of a special 
commission of army surgeons appointed for the purpose. It was 
shown that although excellent preventive measures had been recom- 
mended in circulars issued by the Surgeon-General of the Army, these 
instructions were not carried out in many camps and that the excre- 
ment of the troops had not been properly cared for. Flies were found 
to swarm over the infected fecal matter in the pits and then proceed 
to the mess tents and feed upon the food prepared for the soldiers. 
This was convincingly shown by the fact that where lime had been 
sprinkled over the pits flies with their legs whitened by the lime were 
found upon the mess tables. In the report published by one of the 
members of the commission a number of significant and interesting 
facts relating to typhoid fever were brought out. It was shown, for 
example, that the virulent germs may be excreted by a person for 
some time before he is known to have typhoid. It was also shown 
that such germs may be found in the excrement for a long time after 
