president's address — SECTION L. 263 



It is true that different species of bacteria vary greatly in their 

 power of endotoxin production. The bacillus of blackquarter, 

 that of typhoid fever, Shiga's dysentery bacillus, and Bordet's 

 whooping-cough bacillus all produce notable amounts of toxin. 



The tubercle bacillus and Bacillus mallei produce poisonous 

 materials which, strangely enough, are only slightly toxic for 

 healtJiy animals, but highly so for animals themselves the sub- 

 jects of tuberculosis or glanders respectively. 



But none of these organisms, or cultures of them, are able to 

 provoke the production of antitoxins when injected intO' animals. 

 Further, the researches of Vaughan (1913), Friedberger and 

 others tend to show that the so-called endotoxins ai*e really only 

 protein-cleavage products of the bacterial protoplasm, not poisons 

 specific tO' each species of bacterium, but varying in toxicity 

 according to tha accumulation and distribution of the bacteria in 

 the body, and the rate or rapidity of their breakdown, (lysis) by 

 the serum of the animal host. 



More nearly allied tO' the class of exotoxins or true toixins are 

 the ha-moto.i-inf; and leiococidins produced by certain organisms. 

 Many observers have noticed the effects of stapht/locorci on leuco- 

 cytes in cases of suppuration. Tubercle bacilli have a similar 

 necrosing effect. In a similar fashion stre ptoroccl have a hsemo- 

 lytic effect on red cells, as also have tetanus cultures, and to some 

 extent anth'-ax, B. jji/ocyancii'!, and staphylococci. 



These substances lead naturally to a consideration of the so- 

 called "aggressins" of Bail, and '"virulins" of Rosenow. 



Bail has }>redicated the idea of a secreticrn. on the part oi bac- 

 teria of substances, "aggressins," which are negatively chemio- 

 tactic, preventing phagocytosis and so' allowing the bacteria to 

 multiply until there is an accumulation sufficient to overwhelm 

 the defence. These* "agressins" may be looked upon as the bac- 

 terial response, or counter-move, to the animal's body development 

 of antibodies, and this hypothesis appears to' lend an explanation 

 for the exaltation of virulence produced by growing an organism 

 in a medium containing serum derived from an animal immunized 

 against that organism. 



The use of natural aggressins (/.(., a bacteria-free peritoneal 

 exudate from an animal just dead as the result of inoculation 

 intraperitoneally with a virulent organism), was shown by Bail 

 to reinforce a sublethal dose of a culture and make it lethal, and 

 further, a suitable administration of the aggressin gave rise to 

 immunity (by producing " anti-aggressins " in the animal body). 

 This method of immunizing is now being used in certain diseases, 

 notably blackquarter, though with what degree of success one can- 

 not yet say. 



