26 BIOLOGICAL LECTURES. 



Brieger and Ehrlich (1892). A female goat was immunized 

 against tetanus by the daily injection of " thymus tetanus 

 bouillon." The dose was gradually increased from 0.2 c.c. to 

 10 c.c. At the end of thirty-seven days a mouse, which 

 received o.i c.c. of the milk of this goat in the cavity of the 

 abdomen, proved to be immune against tetanus. Further 

 experiments gave a similar result, even when the milk of the 

 goat was not injected into the peritoneal cavity of the mouse 

 until several hours after inoculation with a virulent culture of 

 the tetanus bacillus. 



In a subsequent communication (1893) Brieger and Ehrlich 

 describe their method of obtaining the antitoxin of tetanus 

 from milk in a more concentrated form. They found by experi- 

 ment that it was precipitated by ammonium sulphate and mag- 

 nesium sulphate. From twenty-seven to thirty per cent of 

 ammonium sulphate added to milk caused a precipitation of 

 the greater part of the antitoxin. This precipitate was dis- 

 solved in water, dialyzed in running water, then filtered and 

 evaporated in shallow dishes at 35 C. in a vacuum. One liter 

 of milk from an immune goat gave about i gm. of a trans- 

 parent, yellowish-white precipitate, which contained fourteen 

 per cent of ammonium sulphate. This precipitate had from 

 four hundred to six hundred times the potency of the milk 

 from which it was obtained in neutralizing the tetanus toxin. 



A most interesting question presents itself in connection 

 with the discovery of the antitoxins. Does the animal which 

 is immune from the toxic action of any particular toxalbumin 

 also have an immunity for other toxic proteids of the same 

 class ? The experimental evidence on record indicates that it 

 does not. In Ehrlich's experiments with ricin and abrin he 

 ascertained that an animal which had been made immune 

 against. one of these substances was quite as susceptible to the 

 toxic action of the other as if it did not possess this immunity, 

 i.e. the antitoxin of ricin does not destroy abrin, and vice versa. 

 As an illustration of the fact he states that in one experiment 

 a rabbit was made immune for ricin to such an extent that the 

 introduction into its eye of this substance in powder produced 

 no inflammatory reaction ; but the subsequent introduction of 



