Nil. TYPHOID PLY, OB HOUSE PLY. 27 
than it has hitherto assumed. Perhaps even under city condition* 
it mu>t assume third rank next to water and milk." 
It Is not alone a- a carrier of typhoid thai this fly i- to be feared. 
In the same way it may carry nearly all the intestinal diseases. It i- 
a prime agent in the spreading of summer dysentery . and in this w ay 
is unquestionably responsible for the death of many children in sum- 
mer. One of the earliest accurate scientific studies of the agency of 
insects in the transfer of human disease was in regard to Hie- as 
spreaders of cholera. The belief in this agency long preceded its 
actual proof. Dr. (I. E. Nicholas, in the London Lancet. Volume II. 
L873, page 7-J-1-. is quoted by Xuttall as writing as follows regarding 
the cholera prevailing at Malta in L849: "My first impression of the 
possibility of the transfer of the disease by (lies was derived from the 
observation of the manner in which these voracious creatures, present 
in great numbers, and having equal access to the dejections and food 
of patients, gorged themselves indiscriminately and then disgorged 
themselves on the food and drinking utensils. In L850 the Superb^ 
in common with the rest of the Mediterranean squadron, was at sea 
for nearly six months; during the greater part of the time she had 
cholera on hoard. On putting to sea, the flies were in great force; 
hut after a time the flies gradually disappeared, and the epidemic 
slowly subsided. On going into Malta Harbor, but without com- 
municating with the shore, the flies returned in greater force, and the 
cholera also with increased violence. After more cruising at sea, the 
flies disappeared gradually with the subsidence of the disease." 
Accurate scientific bacteriological observations by Tizzoni and 
Cattani in 1886 showed definitely active cholera organisms in the 
dejecta of flies caught in the cholera wards in Bologna, Italy. These 
observations were subsequently verified and extended by Simonds, 
Olfelmann. Macrae, and others. 
With tropical. dysentery and other enteric diseases practically the 
same conditions exist. In a report by Daniel D. Jackson to the 
committee on pollution, of the .Merchants' Association in New York, 
published in December, 1907, the results of numerous observations 
upon the relation of flies to intestinal diseases are published, and the 
relation of death.- from intestinal diseases in New York City to the 
"Dr. John It. Mohler, of the Bureau of Animal Industry, IT. S. Department 
of Agriculture, informs the writer that investigations made in his office show- 
that typhoid bacilli will live in butter under common market conditions for 151 
days and still be able to grow when transferred to suitable conditions, in 
milk under market conditions they retain active motility for 20 days, after 
which time there is a gradual lessening in numbers until, on the forty-third day 
of t he test, they <iis;i i ipea r from view. At certain seasons of the year large num- 
bers of Hies collect upon the vats in which milk and cream are being stored 
in dairies and creameries. Many of the Hies fall in. their bodies being strained 
out when the cream is sent to the churn. If any of these Hies carry typhoid 
bacilli these are washed off by the milk and remain in the butter or cheese 
made from it. Thus the eating of butter contaminated in this way may account 
for vi'ry many cases of typhoid fever the cause of which cau not be otherwise 
traced. 
