NEUTRALISATION OF SIMPLE POISONS 203 



rabbits than with guinea-pigs. 1 But perhaps this differ- 

 ence depends only upon the different mode of injection 

 (intra-venous respectively intra-peritoneal). 



In the same manner behaves, according to the researches 

 of Madsen and Walbum, 2 ricin and its antibody, at least 

 in so far as the agglutinating action of ricin on red 

 blood-corpuscles (of rabbits) is concerned. The agglu- 

 tinating power of the ricin was measured by observing 

 the limpidity of 5 c.c. of a one per cent suspension of red 

 blood-corpuscles added to 2 c.c. of the solution and there- 

 after held at 37 C. for 20 minutes. As example may serve 

 the following figures : 



n =o 0.025 0.035 -45 o -55 0.065 -75 0.087 o- 1 

 ?obs. =6.7 6.7 3.6 2.1 1.5 1.0 0.8 0.64 <o.5 

 ?caic. = (i9'7) 6 - 8 3- 6 2 - 1 M 1.0 0.8 0.63 0.12 



One c.c. of the antiricin, prepared by injection into a 

 goat, was equivalent to 29 c.c. of the solution of ricin em- 

 ployed (containing i per cent of a ricin preparation from 

 Merck). The constant of equilibrium was ^=0.0537. The 

 formula was the same as that used for tetanolysin. 



As is evident from these figures, the prototoxoid phe- 

 nomenon is very marked. No sensible neutralisation takes 

 place until about 0.75 equivalents of antitoxin have been 

 added. But this phenomenon was "very inconstant, and 

 was observed in only half the number of the cases exam- 

 ined." The authors could not determine what accidental 

 circumstances could have caused this contradictory be- 

 haviour of ricin ; the so-called prototoxoid effect was 



1 British Medical Journal, Sept. 10, 1904, p. 14. 



2 Madsen and Walbum: Centralbl. f. Bakteriologic, Abt. I., 36. 242 (1904). 



