44 
Toxicity of normal horse serum (our roan). 
Xo. 
G. P. 
1 
' First injection. 
Interval. 
Second injection. 
Eesult. 
7845 
0.24 c. c. toxine 9—^o 
Days. 
58 
5 c. c. normal horse 
Dead, 20 minutes. 
7850 
c. c. antitoxic horse 
serum (A. 192), sub- 
cutaneously. 
0.24 c. c. toxine 9-f 9:^0 
58 
(roan) serum in- 
traperitoneally. 
do 
■ Dead, 18 minutes. 
7725 
c. c. antitoxic horse 
; serum (A. 142), sub- 
cutaneously. 
0.24 c. c. toxine 9— 
i 80 
-1 
I 
i 
Dead, 85 minutes. 
444 
c. c. antitoxic horse 
serum (PD. 08022), 
subcutaneously. 
0.0006 gm. tetanus tox- 
i 
56 
do 
Very severe symp- 
447 1 
ine A-FY 2 V 0 c- c. anti- 
toxic horse serum 
(Hoechst), subcu- 
taneously. 
0.0006 gm. tetanus tox- 
56 
i 
do i 
toms. 
Very severe symp- 
ine A-f 3-^0 c. c. anti- 
toxic horse serum 
( INI. 21 22 ) , subcutane- 
ously. 
1 
toms. 
It is perfectly evident from the above that our results upon the 
comparative toxicity of the French and American serums do not 
agree with those reported by Besredka and Steinhardt. With us, the 
French serums are perhaps somewhat more toxic than our own. We 
believe these contradictory results are due to other causes than the 
relative toxicity of the different serums. It is not likely that these 
differences are due to varying susceptibility of the different breeds of 
guinea pigs. AVe have found little difference between guinea pigs 
obtained from five or six different sources. Further, we have some- 
times been struck with the fact that guinea pigs from our own 
stock and raised under precisely similar conditions show striking dif- 
ferences of degree in the reaction to the second injection. For 
instance, all the guinea pigs sensitized with toxine-antitoxin mixtures 
upon a certain date will subsequently prove exceedingly sensitive, and 
most of them will die at the second injection, whereas another lot of 
guinea pigs similar sensitized at another time will prove much less 
susceptible at the second injection. So far as we are able to judge, 
this difference of toxicity depends upon something connected with the 
sensitizing action and not with the variety of horse serum given at 
the second injection. 
XoTE. — When ioxine is mentioned in the tables diphtheria toxine is meant unless 
otherwise stated. 
