IMMUNITY TO LOCAL SKIN REACTIVITY I3I 



meningococcus "agar washings" filtrates, ^vhen employed in suf- 

 ficiently large doses, may be able to elicit the jjlienomenon in 

 practically all rabbits tested. Thtis, in one group of experiments 

 74 rabbits stnvi\'ed an intravenous injection of a large dose of 

 meningococcus "agar ^vashings" filtrates. Se^■enty-three of these 

 animals showed severe hemorrhagic necrosis. When 6 to 10 menin- 

 gococcus reacting units ^vere used, the percentage of positive re- 

 sults was found to be between 90 to 100 per cent (Sh"^vart7man, 

 i928t>, 1929^/, //) . 



Kielanowski (1935) and Kielano^vski and Selzer (1934/;) cor- 

 roborated the obser\ations of \arious investigators on sponta- 

 neous \ariations in susceptibility of rabbits to the phenomenon. 

 The spontaneous imimniity. ho^vever, appeared to them not as 

 an absolute btit only a relative refractoriness. Whilst they ^vere 

 never able to obtain any rabbits ^vhich did not produce the 

 phenomenon with large doses of the filtrate, there were some 

 rabbits which in\ariably sho^ved a higher degree of stisceptibility 

 (white and blue rabbits) . These authors therefore suggest that 

 the expression "spontaneous immunity to the phenomenon" be 

 replaced by the term "non-reactivity." Stolyh^vo (1935, 1936) 

 also pointed out that the resistance to the phenomenon depends 

 on the dose employed. Although Avith given moderate amotnrts 

 of filtrates the rabbits coidd be grouped as partially susceptible 

 and resistant, the employment of large doses may redtice the 

 ntunber of negative rabbits to zero. Gratia and Linz (1932c) 

 stated that about 60 to 70 per cent of rabbits were susceptible 

 to the phenomenon, ^vhilst 10 to 20 per cent ^vere hypersensitive 

 and died before the reaction took place and approximately 20 to 

 30 per cent ^vere refractory to the phenomenon. According to the 

 same authors, no distinction coidd be made as to the resistance to 

 the phenomenon between males and females. 



Bin net (1931) recorded comj^arative observations on domestic 

 and Avild Australian rabbits. Twice ^vashed, killed bacteria were 

 efTecti\e in eliciting the skin-preparation as ^vell as the reaction. 

 Domestic rabbits reacted readily to stich preparations but ^vild 

 Australian rabbits gave iew positive reactions when ^vashed bac- 

 teria Avere used as the provocative factors. As pointed otit in Chap- 

 ter ni, Avashed bacteria contain only a small amount of active 

 principles. On the basis of Burnet's observation, the interpreta- 

 tion may be made, therefore, that Avild Australian rabbits pos- 



