9 
Immunity Against Hemorrhagic Septicemia 
The results of the preceding tests are summarized in Tables 
12 and 13 and they show that the protective influence of the 
serum was quite manifest, altho it does not appear that the 
variation in the doses as used in the series was very strikingly 
shown in the totals. There were differences, but they were 
neither conspicuous nor consistent. There appears, however, to 
be a marked difference in the potency of some of the sera ex- 
amined. The tables show that protective influence of the sera 
examined manifested itself in two ways, — in the first place by 
actually preventing the death of experimental animals when 
injected with virulent cultures, and in the second place by in- 
creasing the approximate surviving period, after virus inocu- 
lation, of the serum-treated animals which actually succumbed, 
as compared with the ones treated with normal serum and with 
those which served as virus controls. 
Of the 69 rabbits treated with serum and virus, 26 survived. 
Approximately two weeks after the latter had received the first 
virus injection, they were inoculated again with the same virus. 
Table Xo. 14 shows that none of those survivors had become 
resistant to infection as a result of the serum-virus treatment 
they had previously received. A certain lengthening of the sur- 
viving periods after the last virus injection could be observed. 
(See Table 15.) 
