REACTIVITY OF MALIGNANT NEOPLASMS 257 



which rarely or never regress, ra{)iclly growing malignant tumors 

 which eventually regress (heterologous grafts) and benign em- 

 bryomas or granulomas, rapidly developing, ^vhith exentiially 

 regress. 



Experiments ot various authors tend to show that the reaction 

 in the tumor described here depends on the presence of active 

 principles of the phenomenon of local tissue reactivity in the 

 material used. This contention is brought out clearly by com- 

 parative studies on the effect of active principles and a variety 

 of non-bacterial substances. Positive results obtained wdth various 

 non-bacterial substances are rare and cannot be reproduced with 

 regularity. Substances affecting normal blood vessels (gold chlo- 

 ride, Crotalus adenamentus) fail to produce lesions in the tumors. 

 Conversely, the active principles of the phenomenon eliciting 

 the dramatic effect upon the tiunors produce no effect Avhatsoever 

 upon the blood \essels and tissues of mice and rats treated. 

 (Apitz.) 



Considerable piuification and concentration of the tiniior-de- 

 stroying properties was also reported by Shear and Andervont. 

 The concentration of the phenomenon-producing potency of 

 their preparation paralleled the ttmior-destroying potency. 



There is observed a decidedly higher death rate following in- 

 jections of bacterial filtrates in tiunor-bearing mice as compared 

 with normal mice. Attention is drawn to the possible role which 

 sensitization with secondary bacterial invaders may play in the 

 j)roduction of this high death rate. The process of ttmior destruc- 

 tion is not necessarily directly responsible for the high death rate. 



In certain proportions, mixtures of B. typJiosiis "agar wash- 

 ings" nitrates ^vith homologous antisera possess a comparatively 

 lo\v lethal potency and yet elicit prompt and intense hemorrhagic 

 necrosis and subsequent complete regression of sarcoma 180 in 

 a high percentage of mice, ^vell above normal expectancy. 



Spontaneous infections with B. enteritidis and infections in- 

 duced with rough B. enteritidis of low virulence exert a striking 

 and inhibitory influence upon the development of mouse sar- 

 coma 180. There exists a definite correlation between the ability 

 of a filtrate of a given microorganism to elicit the phenomenon 

 of local tissue reactivity in rabbits and the inhibitory effect of 

 the infecting microorganisms upon the development of sarcoma 

 180 in mice. 



