76 
nearh" this percentage of tricresol. As the serums practically never 
contain an excess of preservatives, these inoculations into mice serve 
as a further test for tetanus and other poisons. 
Finallv, all that is Ifeft of the serum is injected into the peritoneum' 
of a guinea pig in order to discover the presence of any virulent sub- 
stance of a bacterial or toxie nature. 
These tests are repeated with sufficient frequency to establish the 
fact that the serums made by each licensed manufacturer sold upon 
the market are pure and potent. 
Tables found very useful for diluting the serum in making these 
tests follow: 
TABLE FOB DILUTIXG SERUMS 100 TO 500 EXITS PER CUBIC 
CEXTUIETER. 
First dilution . 
1 + 9 = 1:10 1 c. c.=0.1 
Second dilution . 
1 of 1st dil. — 
+ 9 = 1:100 - 
1 
c. 
c. 
= 0.01 
or 
1 — 
10 0 — 
100 units 
per 
c. 
c. 
+ 10 = 1:110 
1 
c. 
c. 
= 0.00999 
or 
1 — 
110 — 
110 units 
per 
c. 
c. 
+11 = 1:120 
1 
c. 
c. 
= 0.00833 
or 
1 — 
12 0 — 
120 units 
per 
c. 
c. 
+12 = 1:130 
1 
c. 
c. 
= 0.00769 
or 
1 — 
13 0 — 
130 units 
per 
c. 
c. 
+ 13 = 1:140 
1 
c. 
c. 
= 0.00714 
or 
1 — 
14 0 — 
140 units 
per 
c. 
c. 
+14=1:150 
1 
c. 
c. 
= 0.00666 
or 
1 — 
15 0 — 
150 units 
per 
c. 
+15 = 1:160 
1 
c. 
c. 
= 0.00625 
or 
1 — 
16 0 — 
160 units 
per 
c. 
c. 
+16=1:170 
1 
c. 
c. 
= 0.00588 
or 
1 — 
17 0 — 
170 units 
per 
c. 
c. 
+17=1:180 
1 
c. 
c. 
= 0.00555 
or 
1 — 
18 0 = 
180 units 
per 
c. 
c. 
+ 18 = 1:190 
1 
c. 
c. 
= 0.00526 
or 
1 — 
19 0 — 
190 units 
per 
c. 
c. 
+19 = 1:200 
1 
c. 
c. 
= 0.005 
or 
1 — 
Jo 0 — 
200 units 
per 
c. 
c. 
+ 20 = 1:210 
1 
c. 
c. 
= 0.00476 
or 
1 — 
2 10 — 
210 units 
per 
c. 
c. 
+ 21 = 1:220 
1 
c. 
c. 
= 0.00454 or 
1 — 
2 2 0 “ 
220 units 
per 
c. 
c. 
+22 = 1:230 
1 
c. 
c. 
= 0.00434 or 
1 — 
2 3 0 — 
230 units 
per 
c. 
c. 
+ 23 = 1:240 
1 
c. 
c. 
= 0.00416 
or 
1 — 
J4 0 — 
240 units 
per 
c. 
c. 
+ 24=1:250 
1 
c. 
c. 
= 0.004 
or 
1 — 
J5 0 — 
250 units 
per 
c. 
c. 
+25 = 1:260 
1 
c. 
c. 
= 0.00384 
or 
1 — 
2 6 0 — 
260 units 
per 
c. 
c. 
+26=1:270 
1 
c. 
c. 
= 0.0037 
or 
1 — 
2 7 0 — 
270 units 
per 
c. 
c. 
+ 27 = 1:280 
1 
c. 
c. 
= 0.00357 
or 
1 — 
2 8 0 — 
280 units per 
c. 
c. 
+28=1:290 
1 
c. 
c. 
= 0.00345 
or 
1 — 
J9 0 — 
290 units 
per 
c. 
c. 
