SPECIFIC BACTERIAL PRODUCTS 455 



about the site of inoculation. Hiss and Zinsser 24 state that 

 the production of aggressins by pathogenic bacteria is probably 

 absent in test tube cultures, but is called forth in the animal 

 body by the effect of the germicidal or other influences en- 

 countered by the organisms after inoculation. Aggressins, 

 therefore, are the substances present in sterilized exudates re- 

 sulting from the infection with several if not all of the patho- 

 genic bacteria and which when injected with the specific viru- 

 lent organisms, cause them to produce death in an unusually 

 brief time. The theory that the aggressins consist of endo- 

 toxins liberated by the bacteria has been attacked by Wasser- 

 mann and Citron 25 and by "Wolf. 26 These investigators claim 

 that much of the aggressive power of the exudates is due to 

 their containing liberated bacterial poisons. 



It has been found possible to immunize animals against 

 certain infections by repeated injections of aggressins in the 

 form of exudates, which results in the formation of "anti- 

 aggressins, " which inhibit the action of the aggressin thereby 

 permitting phagocytosis to take place. Bail divided the bac- 

 teria according to their power to produce an aggressin and 

 consequently to their ability to invade the animal body into 

 "pure parasites," "half parasites" and "saprophytes," the 

 last being unable to live in the animal tissues because of the 

 total absence of aggressins. Further investigations on the 

 nature of aggressins are necessary before any very definite 

 conclusions can be drawn concerning them. The theory as 

 put forth by Bail is of assistance in explaining the phenomenon 

 of virulence or difference in the degrees of pathogenesis of 

 many bacteria. 



Anaphylaxis. Hericourt and Richet 2T found that re- 

 peated injections of eel-serum into dogs gave rise to an in- 



24 Hiss and Zinsser. loc. tit. p. 293. 



23 Wassermann and Citron. Deut. med. Woch., Bd. XXXI (1905) 

 p. 573. 



Lr 'Wolf. Centralbl. f. Bakt., Bd. XXXVII (1904) pp. 390, 566, 684. 



27 Hericourt and Richet. Comp. rendu de la Soc. de Biol.., 10 serie 

 Vol. V (1898) p. 137. 



