76 
nearh^ this percentag-e 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. 
Finally, all that is left 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 toxic 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 FOR DILUTIXG SERUMS 100 TO 500 EXITS PER CUBIC 
CEXTIMETER. 
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 — 
120 — 
120 units per 
c. c. 
+ 12 = 1:130 
1 
c. 
c. =0.00769 or 
130 units per 
c. c. 
+ 13 = 1:110 
1 
c. 
c. =0.00711 or 
1 — 
14 0 — 
110 units per 
c. c. 
+11 = 1:150 
1 
c. 
c. =0.00666 or 
1 — 
15 0 
150 units per 
c. c. 
+15 = 1:160 
1 
c. 
c. =0.00625 or 
1 — 
160 — 
160 units per 
c. c. 
+16=1:170 
1 
c. 
c. =0.00588 or 
1 — 
lYO — 
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 — 
T¥0 — 
190 units per 
c. c. 
+ 19 = 1:200 
1 
c. 
c. =0.005 or 
wwiy — 
200 units per 
c. c. 
+ 20 = 1:210 
1 
c. 
c. =0.00176 or 
1 — 
^TO — 
210 units per 
c. c. 
+21 = 1:220 
1 
c. 
c. =0.00151 or 
1 — 
¥20 — 
220 units per 
c. c. 
+22 = 1:230 
1 
c. 
c. =0.00131 or 
1 — 
¥3 0 — 
230 units per 
c. c. 
+ 23 = 1:210 
1 
c. 
c. =0.00116 or 
1 — 
¥4 0 — 
210 units per 
c. c. 
+ 21=1:250 
1 
c. 
c. =0.001 or 
2^iw~ 
250 units per 
c. c. 
+25 = 1:260 
1 
c. 
c. =0.00381 or 
1 — 
¥6 0 
260 units per 
c. c. 
+26 = 1:270 
1 
c. 
c. =0.0037 or 
1 — 
¥T¥ — 
270 units per 
c. c. 
+ 27 = 1:280 
1 
c. 
c. =0.00357 or 
1 — 
¥8 0 — 
280 units per 
c. c. 
+28 = 1:290 
1 
c. 
c. =0.00315 or 
¥¥0 = 
290 units per 
c. c. 
