NEUTRALISATION OF H^EMOLYSINS l8l 



given a much smaller value of the increase, which amounts 

 only to the proportion i : 1.91 between 16 and 37 C. 1 A 

 great difficulty inherent in the determination of the con- 

 stants of tetanolysin, as well as of other poisons, lies in the 

 circumstance that the constant of equilibrium is rather dif- 

 ferent for different preparations of the poison. Fresh 

 specimens of tetanolysin seem to give lower constants 

 than old ones. In general the constant of fresh teta- 

 nolysin seems to lie rather near to 0.12 at 20 C. (room 

 temperature). 



From the variation of K with temperature it is possible 

 to calculate the heat of reaction which is developed in the 

 combination of one grammolecule of tetanolysin with one 

 of antitoxin to form two of the reaction-products. A 

 change in the proportion of I : 1.91 in the interval be- 

 tween 1 6 and 37 C. corresponds to a development of 

 5480 calories. 



As we have seen above (cf. p. 41), tetanolysin is rap- 

 idly decomposed in temperatures in the neighbourhood 

 of 50. An elevation of the temperature of 3.7 degrees 

 increases the constant of velocity in the proportion 16.8 : 1. 

 At 49.8 C. the rate of destruction is of such a magnitude 

 that a poisonous solution loses half its strength in 62 min- 

 utes. From these it is easy to calculate that at 20.2 and 

 5.4 degrees it will require 6.6 xio 9 and 5.3 x io 14 hours 

 (i.e. 7.5 x io 5 and 6.2 x io 10 years) respectively to descend to 

 half its strength. Now it is often observed that solutions 

 of tetanolysin weaken very rapidly, thus, for instance, it may 

 lose about five-sixths of its haemolytic power within five days 



iMadsen and Arrhenius: Medd. fr. Vet.~Ak : s. Nobelinstitut, 1. No. 3, 

 5 



