210 MANUAL OF BACTERIOLOGY. 



There is little, if any, analogy, on the other hand, between 

 the tolerance acquired by gradual dosage from bacterial and 

 other toxins and that which victims of the morphine and 

 cocaine habits have for immense doses of these drugs, for no 

 bodies resembling antitoxins are obtained from animals that 

 have been accustomed to such drugs. 



The gradual injection of animals with bacteria which produce 

 endotoxins, B. typhosus, B. choleras Asiaticae, B. coli communis 

 and others, does not produce antitoxin. It sometimes seems 

 to have no effect, at others it seems to increase the bacteriolytic 

 power of the blood for the bacteria with which the animal is 

 injected. Frequently it has a most peculiar effect. This 

 peculiarity was first shown by Loeffler and Abel* in experi- 

 ments upon guinea-pigs injected with colon bacilli at the same 

 time given injections of colon-immune dog's serum. The very 

 unexpected result was obtained that those guinea-pigs which 

 received smaller doses of the immune serum were protected, 

 whereas those injected with larger doses were not protected. 

 Similarly, Neisser and Wechsberg found in test-tube experi- 

 ments with cultures that the serum from the injected animal 

 sometimes kills the kind of bacteria used for injection when 

 it is diluted but not when it is undiluted. This action is so 

 paradoxical that it may well be stated in other words for 

 emphasis. The normal blood-serum of uninoculated animals, 

 as has been previously stated, is bactericidal for many bacteria. 

 Now, if an animal furnishing normally highly bactericidal 

 serum is injected with an endotoxic bacterium, its blood-serum 

 often fails to kill the [kind of bacterium with which it is in- 

 jected, unless the serum is greatly diluted. It still retains its 

 power to kill other kinds of bacteria.t The peculiar behavior 



*Loeffler, F., and Abel, R. Ueber die spezifischen Eigenschaften der Schutz- 

 korper im Blute typhus- und coli-immuner Tiere. Cent. f. Bakt., Abt. i, Bd. 

 19, No. 2, 3, p. 51-70. Jena, Jan. 23, 1896. 



fB. H. Buxton. Bacteriolytic Power of Immune Serum and the Theory of 

 Complement Diversion. Journal of Medical Research, V. XIII., No. 5. (Whole 

 No. 90, N. S. V. S.) p. 431-485. Boston, Aug. 1905. 



