
1905.]| Chemistry of the Toxin-Antitoxin Reaction. 185 
in equilibrium, gradually increasing quantities of lysin were added. The 
same quantities of lysin were added to a second series containing 1 cc. of the 
residue of No. 3, and to a third series containing 1 c.c. of saline. The test 
blood was added to each and, after mixing, the tubes were placed at 37° C. for 
3 hours. The hemolytic indices obtained are shown in Table IT. 
Table II. 

Hemolytic indices. 



Lysin Kxu i 
oe Original | Residual | Original | Residual 
Ge Saline. mixture, fluid, mixture fluid 
No. 3. No. 3. increments. | increments. 
| 
0 0 25 48°2 — — 
0:0001 0 25 48:2 0 0 
0:001 0 25 48°2 0 0 
0:01 2°3 25 48:2 0 0 
0-1 100 o0°2 55:0 8°2 6°8 
0:2 100 41°4 59-1 16°4 10°9 
0:3 100 50°9 63°2 25°9 15:0 
0:4 100 59°] 67°2 34°] 19-0 
Obviously the original mixture has neutralised a very considerable 
proportion of the added lysin, for 0-1 cc. of the lysin causes complete 
hemolysis in saline (index 100), whereas 0:3 cc. in the mixture only 
produces half the effect (index 50°9). The residue, although itself more 
hemolytic than the original mixture, shows a higher neutralising value 
than the latter, as may be seen from the ratio of the increments, Table II. 
If the hemolytic indices of mixtures containing a high concentration of 
antilysin such as those investigated above, are approximate measures of the 
free lysin present, then, for both original and residue, the amount of added 
lysin left free is roughly proportional to the lysin added. The amount 
of added lysin left free by the original is approximately double that left 
free by the residue, which agrees with the conclusion that the free antilysin 
in the latter is present in greater concentration than in the former. 
On the Reversibility of the Reaction —tThe reversibility of the reaction will 
be demonstrated if, on removing the free lysin, the compound of lysin with 
antilysin dissociates, producing more free lysin; on the other hand, if no 
lysin be set free, the reaction is irreversible. In the case of the reaction 
VOL. LXXVI.—B. O 
