442 



Dr. Paul Ehrlich. 



HafFkine, and quite recently by Wright in your own country for 

 typhoid fever, have been arrived at in this way. 



The most interesting and important substances arising during 

 such an immunising process are without doubt the bacteriolysines, 

 in the investigation of which Pfeiffer has done such yeoman's service. 

 How really wonderful it is that after the introduction of the cholera- 

 vibrio into the animal body a substance is formed endowed with the 

 power of dissolving the cholera vibrio, and that vibrio only ! 



This seemingly purposeful and novel phenomenon seems at first 

 sight to have nothing to do with those forces which are normally at the 

 disposal of the organism. It was of the greatest importance to explain 

 the origin of these substances from the standpoint of cellular physi- 

 ology. The solution offered very considerable difficulties, and was first 

 attained when instead of bacteriolysines, hsemolysines came to be 

 employed in experiments. Hsemolysines are peculiar toxic bodies, 

 which destroy red blood corpuscles by dissolving them. Haemolysines 

 may occur in a normal blood when they exercise a solvent action on 

 the red blood corpuscles of other species, or they may be artificially 

 produced, in which case, after an animal has undergone a process of 

 immunisation against the blood corpuscles of another species, there 

 appear in the serum hsemolysines which destroy the kind of blood 

 corpuscles employed in the production of the immunity. In their 

 essential characters they are absolutely comparable with the bacterio- 

 lysines : but they possess over them the great advantage that they 

 admit of being employed in test-tube experiments, and thus aff'ord 

 opportunity for exact quantitative work altogether independent of the 

 variability of the animal body. 



Belfanti and Carbone first discovered the remarkable fact that 

 horses which have been treated with the blood corpuscles of rabbits 

 contain in their serum constituents which are poisonous for the 

 rabbit, and for the rabbit only. While the serum of the normal horse, 

 to the quantity of 60 c.c, could be intravenously injected without 

 harm to the rabbit, a very few c.c. of serum from horses previously so 

 treated with rabbit's blood, proved fatal. 



Bordet showed shortly thereafter, that in the case quoted there was 

 present in the serum a specific hsemolysine which dissolved the blood 

 corpuscles of the rabbit. He also proved that these hsemolysines — as 

 had already been shown by Buchner and Daremberg in the case of 

 similarly acting bodies which are present in normal blood — lost their 

 solvent property on being maintained during half an hour at a tem- 

 perature of 55° C. Bordet added, further, the new fact, that the 

 blood-solvent property of these sera which had been deprived of solvent 

 power by heat, the solvent action could be restored if certain normal 

 sera were added to them. 



By this important observation an exact analogy was established with 



