208 MICROBES AND TOXINS 



anthrax if it is inoculated with a very fine needle so as not to 

 provoke a haemorrhage at the point of inoculation.'^ 



Immunity towards toxins could be made to furnish analogous 

 examples in abundance ; it will be discussed in the next 

 chapter. 



In many cases Pfeiffer has seen his guinea-pigs, which had 

 been thoroughly immunized against the cholera vibrio, succumb 

 to the injection of a moderate dose of vibrios. Yet the serum 

 of these guinea-pigs was capable of producing PfeifTer's phe- 

 nomenon.^ 



Tuberculin carefully employed exerts a favourable effect in 

 many tuberculous patients, and leads to the production of 

 antibodies in their serum. Jochmann has quite recently made 

 several observations of this kind under the direction of R. Koch, 

 and has sought for a correspondence between the appearance 

 and quantity of the antibodies and the resistance of the 

 patient. He found it was impossible to maintain that the 

 presence of antibodies meant recovery. Certain patients mani- 

 fested great clinical improvement simultaneously with the 

 appearance of antibodies ; in others, the improvement was 

 quite as great without the antibodies, while in other cases the 

 appearance of the antibodies coincided with marked and fatal 

 aggravation of the malady. It is -obviously impossible to draw 

 any conclusion as to the immunity of these patients from such 

 in vitro experiments. 



' In this example of the rat there is no question of an antibody produced 

 by immunization, but rather of a want of agreement between the natural 

 immunity of the animal and the natural bactericidal power of the serum. 



^ Quite recently Citron has shown that the serum of rabbits actively 

 immunised against the so-called bacillus of hog-cholera possesses protective 

 properties for guinea-pigs, whereas it has none of this for fresh rabbits. 

 Rabbits prepared with extracts of the bacilli and without active immunity 

 of their own (they succumbed to the test inoculation of living bacilli), 

 nevertheless furnished a protective serum for guinea pigs. Choukewitch 

 taking up this question again, prepared rabbits by large intravenous 

 inoculations of the same bacilli, but in the killed condition. One rabbit 

 of the lot acquired immunity towards the living microbes, but in every one 

 of the series, not only the immune individuals but also the non-immune, 

 the blood contained an abundance of antibodies, immune-bodies, opsonins, 



etc It even contained much more than the serum of rabbits 



rendered truly immune by subcutaneous inoculations of virulent bacilli. 



