Ill 
Of the 523 cases studied in 1907, about 13 per cent, and of the 
747 cases in 1906 only about 4 per cent gave a history of association 
with previous cases in the febrile stage and were attributed to 
infection by direct contact. 
In the number of cases attributed to infection by direct contact 
are not included cases giving a history of association with previous 
cases but which, on account of the precautions being taken and the 
conditions generally, were considered more probably attributable to 
some other factor, such as milk. 
The following table gives the intervals in days elapsing between 
the definite onset of illness of the 66 secondary cases and the definite 
onset of the primary cases from which these 66 cases were consid- 
ered to have contracted the infection, the figures for the cases studied 
in 1907 being placed in a parallel column: 
Number of days elapsing between 
onset of primary and secondary 
cases. 
Numbei 
ondarj 
1908. 
r of sec- 
' cases. 
1907. . 
0 
2 
8 
3 
3 
9 
2 
4 
10 
1 
3 
11 
0 
3 
12 ■ 
1 
2 
13 
3 
0 
14 
1 
1 
15 
1 
0 
16 
1 
1 
1" 
t 
0 
1 i 
18 
3 
2 
19 
0 
2 I 
20 
3 
1 
21 
1 
1 ! 
3 
1 i 
24 
0 
2 i 
25 
0 
3 I 
97 
0 
1 i 
28 
0 
2 
29 
2 
I 
2 ' 
30 
1 
2 
31 
1 
1 
32 
1 i 
0 
33 
1 
2 1 
1 
34 
1 
0 
35 
3 
1 
36 
0 
1 
37 
2 
0 
38 
1 
0 
39 
2 
1 
40 
3 
1 
41 
0 
1 
44 
1 
1 
