20 THOMPSON YATES LABORATORIES REPORT 
benefit in the larger dose of metabolised broth. Moreover, if the Rabbits became ill it would be 
from plague, since the culture was not sterilized ; and if more recovered after receiving the larger 
dose than was the case with those receiving the lesser it would show that the larger dose of 
metabolised broth tended to lower the case mortality. 
Seventeen Rabbits were inoculated with a broth culture of plague from the laboratory stock. 
Letter P denotes that a post-mortem examination was made and the plague bacillus recovered from 
the heart blood. 
Experiment I 
No. 
Weight. 
Result. 
I . 
. 2,020 grams 
inoculated 
with 0.175 c.cm. 8 days old living 
culture ... Survived. 
2 . 
• 1480 „ 
„ 0.25 
„ ... Died in 64 hours, P. 
3 • 
• 1)9 10 „ 
„ 0.5 
„ ... Survived. 
+ • 
• i,+7o » 
„ 0.75 
„ ... Died in 20 hours. P. 
=; • 
• 1,5+0 
„ i.o „ „ „ 
,, ... Died in 64 hours. P. 
6 . 
• 1,810 „ 
„ 1-25 
„ ... Survived. 
7 • 
• 1,750 „ 
,, ... Survived. 
Experiment II 
No. 
Weight. 
Result. 
8 . 
. 1,000 grams 
inoculated 
with 0.5 c.cm. 8 days old living c 
ulture ... Died in 75 hours. P. 
9 • 
• 1,050 „ 
„ 0.75 „ 
... Died 6th day. No P.-M. 
ID . 
• 1,300 „ 
,, 1.0 ,, „ „ 
... Died in 60 hours. P. 
. i,+5o „ 
„ 1.25 „ 
„ ... Died in 60 hours. P. 
1 2 . 
. 1,280 „ 
„ 1-5 
„ ... Survived. 
13 • 
• i,4-8o „ 
„ 1-5 
„ ... Survived. 
Experiment III 
No. 
Weight. 
Result. 
H ■ 
. 1,750 grams 
inoculated 
with 0.5 c.cm. 1 1 days old living c 
ulture ... Died 6th day. No P.-M. 
15 • 
• 99° 
„ 0.5 „ 
... Died 6th day. NoP.-M. 
i6 . 
. 1,880 „ 
„ ... Survived. 
17 • 
• 940 „ 
„ 1.5 „ 
„ Died 3rd day, 10 hours. P. 
As a control to these, some of the culture that was used for the las't four Rabbits was filtered 
through a porcelain filter, and the microbes were washed off the candle into a quantity of sterilized 
water equal in amount to the broth culture taken. Four Rabbits were inoculated. 
No. Weight. 
18 ... 1,420 grams inoculated with 0.5 suspension 
19 ... 900 „ „ ,, 0.3 ' „ 
20 ... 1,290 ,, „ „ 1-5 ,, 
21 ... 840 „ „ ,,1.5 „ 
Result. 
Died 4 days 20 hours. P. 
Died 5 days 20 hours. P. 
Died 3 days 23 hours. P. 
Died 3 days 22 hours. P. 
Thus, out of 10 Rabbits inoculated with doses of 1 c.cm. and under of living plague broth 
culture, 8 died ; and of 7 Rabbits inoculated with doses over i c.cm. and up to 1.5 c.cm., only 2 
died. It is evident that the larger dose contained sufficient active substance to reduce the mortality, 
and as the cultures were young it is more likely the substance was contained in the broth than in 
the deposit, which would consist almost entirely of living microbes. 
