THE r\ PHOID PLY, OB BOUSE PLY. 
Table 111. Sources of bacteria from ft 
29 
Source. 
Total 
number. 
Total acid 
bacteria, 
Rapid 
liquefy 
Ingbac 
lena. 
Slow 
llquefj 
Ing bac- 
teria. 
BacU /in in 
hirtis 
aeidi. 
Group A. 
Class l. 
( n/, :, TO 
il' II' s. 
i iroup A. 
( !lan 2. 
L907. 
July 27 
m) l fly, bacteriological 
::, 150 
550 
7,980,000 
420.0(H) 
156,000,000 
1,660,000 
183,000,000 
928,000 
lis. 800, oi mi 
6,600,000 
1. 125,000 
17,580 
22,880,1 
880,000 
35.500,000 
822,700 
308, 700 
2 .i 1 
100 
220,000 
11,600 
S,95O,O(i0 
95,800 
2, lio.oiio 
IS, 700 
lo. 180,000 
•_', 182,000 
125,000 
l. 167 
22.. v. 16, ooo 
869,000 
600 





10(1,000 
700 




120,000 
4.600 
too 

July 27 
[b] i fly. bacteriological 
laboratory 
Aug. 6 
e) 19 cow-stable fliea 
Average per fly 
(>i) 94 swill-barrel flies 
Average per By 
(e) in pigpen flics 
Average per flv 
(/) 18 swill-barrel flies.... 
\\ enme per flv 
[g) SO dwelling-house Bies. 
Average per By 
(A i 26 dwelling-house flies. 
Average per fly 
/ 1 10 dwelling-house flies. 
Average per fly 
(j) l large bluebottle 
blowfly 
•jo. 000 
1, Ml III 
II 

266, i 
1. l-o 
l 1,500,000 
804,000 
12,500 
117 
84,000 
L,SO0 
125. Ill II) 
1. 100 
Audi 
Aug. 11 
Bept i 
Sept.21 
1,820,00(1 
16,000 
933,000 
6,500 
10,480,000 
582,000 
1,630,000 
19,800 
1,176,000 
12,200 
30,000,000 
1,600,000 
Sept. 21 
Bept.27 
13,670,000 8,840,000 
121.200 
Aug. 20 
(•) 
Total average of 41 1 flies. . 
Average per Cent of 114 
flies 
1,222,570 
367,300 i 7.830 73.500 
30 
765,000 
25 
6 
230 
6 
268, 700 
8 
Average per fly of 256 
flies, experiments (d), 
(e),and (/) 
3,061,000 
211,500 
18 
Average per cent of 256 
flies, experiments (d), 
- i and ( f) 
" 2,200 mold spores. 
" From the 4 above table the bacterial population of 414 flies is pretty 
well represented. The domestic fly is passing from a disgusting nui- 
sance and troublesome pest to a reputation of being a dangerous 
enemy to human health. A species of mosquito has been demon- 
strated to be the cause of the spread of malaria. Another kind of 
mosquito is the cause of yellow fever, and now the house fly is con- 
sidered an agency in the distribution of typhoid fever, summer com- 
plaint, cholera infantum, etc. 
"The numbers of bacteria on a single fly may range all the way 
from 550 to 6,600,000. Early in the fly season the numbers of bac- 
teria on flies are comparatively small, while later the numbers are 
comparatively very large. The place where flies live also determines 
largely the numbers that they carry. The average for the 414 flies 
was about one and one-fourth million bacteria on each. It hardly 
seems possible for so small a bit of life to carry so large a number of 
organisms. The method of the experiment was to catch the flies from 
the several sources by means of a sterile fly net, introduce them into 
a sterile bottle, and pour into the bottle a known quantity of steril- 
ized water, then -hake the bottle to wash the bacteria from their 
bodies, to simulate the number of organisms that would come from a 
fly in falling into a lot of milk. In experiments ' df ' ef and '/' 
