THE STABHLITY OJ TZTAXFS TOXIXE, 
Fr»:*m a practical 5taiidp:?iiii iz is impi.nant to obtain a stable 
p*jis-zr. Herein lies the cmix tlie problem so far as the standard- 
ization of tetamis antite»xin is concerned. Tetamts toxin e in s«:‘lution 
can not be dependent iifHjn. Its strengtli varies s«3, that if the 
s-dnble fHjisnns are used to meas^rre the value :-f the antitoxic semms. 
as is the case vith the German meth*>i. it is found necessary to 
redetermine by a series of mice the stren^h : f the toxiiie each time 
a sentm is iesie<i. Dit»htheria toxfne in s*:*Intion. after a peri*?d of 
ripening, comes to a sta^ -tf eqnilihriiim and after this period is 
reacLeii retains its toxicity for a !'*n^ time. This fact is of shmai 
service in the standar^iization of diphtheria antitoxin. The fact 
that tetanus tc-xine ices n-: t exhibit the same ctjnstancy in s«;»ItLtion 
has thxovtn miich confrrsion tmd no little drhicTilty into the work of 
standardizing its antitoxin. 
Cbtr £rst elrtrts therefore were tc* obtain a stable p:»is4:»n. In this 
we f orttmately snccee«ie^i by precipitating the filtere«i b*:»mllon culture 
with ammonium sulphate, riry inn the pre*:ipitate over sulphuric acid, 
griniing to an impalpat»ie p«>wder. and presermng in vacuo under 
the influence -‘f gentaph«>sphoric acid — a very strong dehydrating 
substance — ^in a cold, dark place. Under these conditions we have 
fomd the .irie«l m:»is-:‘n maintain- its strength without appreciable 
alteration at least 2b months, as wnl l»e seen by the following table: 
ii30i; V,_.. -L — yZf of uiarejk* A. 

Z'ri.ie. 
z-:3±:fc 
— =■- 
- 
nil*, 
n. 
-i 
^5*5* 
v>.-- 
otoz :o 
iitii 
itiT. 
-00 .< *: 
-- 
£2 
-OX 
3 
i 
M>.r- iz.zyy 
. :tT :i> 
~ i 
-r 
:.-,r 
Az r. A 
.ox :o 
-1, 
- ^ 
- 
Azr. 7 
-OX - x^ 
3 
^ 
Jzzst 'A ICi- 
oix o«> 
-t 
-r--. 
. ;o. ■<> 
1^, 
- _ 
.-XV 
. W- yy 
2* 

-Ju 
xii: 
.-Y 
- XX :o 
r 
4 
2'f 
Sexz. Il-OC*: 
x^ 
V,>T. ts.no: 
-OX- .<> 
-►-•i 
s:- 
. XX - '♦> 
z 
iTt. 
JJOC- 4. ZZr>y. 
.;XX X*- 
3^ 
.yy yy 
X 
X 
jV 
33S. 
- 
.ix«: j> 
i 
'Mr 
«* 
. - j> 
IS 
-:s'- 

- IT55 
3 1?:^ 
- OX. XX 
3 
X 
^ 
. XX- X*- 
■5 
— 
