426 INFECTION AND RESISTANCE 



feld and Dold 83 and Friedberger, 34 suggest that the horse serum 

 absorbed by the kaolin may act as an antigen itself, and is acted upon 

 by normal sensitizer present in the guinea pig serum. This is in 

 keeping with the well-known fact that small amounts of sensitizers to 

 many varieties of foreign proteins are present in normal serum, and 

 is further borne out by the fact that Neufeld and Dold, unlike Keys- 

 ser and Wassermann, were never able to produce anaphylatoxin by 

 allowing the alexin alone to act upon kaolin without previous 

 absorption of horse serum. 



We say "never," though the protocols of Neufeld and Dold 35 

 show a single successful experiment. This they explain, however, 

 by assuming the accidental presence of some antigen in the alexic 

 serum. That is, the entire complex, antigen, sensitize^ and alexin, 

 is assumed to have been present in this particular guinea pig serum. 

 The same explanation may be applied to the occasional inherent 

 toxicity which develops in normal guinea pig sera on standing. 

 Whether the above complicated explanation is necessary or whether 

 we may assume an autolytic process in the guinea pig serum by which 

 anaphylatoxin-like substances are formed is an open question. 



At any rate, it has been shown that, even with bacteria, the 

 action of alexin is not the only way in which acute poisons may be 

 obtained from them. And, indeed, if we look upon the action of 

 alexin as analogous to that of an enzyme an assumption for which 

 we have much supporting evidence, we may well expect that other 

 methods of proteolysis will give similar toxic cleavage products. 

 And various methods of bacterial autolysis have actually yielded 

 such results. Thus Neufeld and Dold obtained poisons by digesting 

 typhoid bacilli, cholera spirilla, and other microorganisms for sev- 

 eral hours in salt solution, lecithin salt solution, and inactivated 

 guinea pig sera. Their extracts killed guinea pigs within several 

 hours. Rosenow 36 has even succeeded in obtaining acutely toxic sub- 

 stances which caused typical anaphylactic death in guinea pigs by 

 suspending pneumococci, typhoid bacilli, and other bacteria in salt 

 solution at 37 C. for varying periods, and the writer, 37 though never 

 producing acute death, was able to cause typical anaphylactic shock 

 in isolated cases with similar salt solution extracts of typhoid bacilli. 

 It is not impossible that poisons obtained in this way are formed 

 by autolysis due to proteolytic enzymes of the bacterial cell. 



In cases in which bacteria, suspended in salt solution and other 

 indifferent fluids, represent the only source of protein present it 

 must, of course, be assumed that they are the substratum or matrix of 



83 Neufeld and Dold. Loc. cit. 



84 Friedberger and Salecker. Zeitschr. f. Imm., Vol. 11, 1911. 



85 Dold. Loc. cit. 



88 Rosenow. Jour. Inf. Dis., Vol. 9, 1911; Vol. 10, 1912. 

 87 Zinsser. Loc. cit. 



