Chapter II 



PHENOMENON OF LOCAL SKIN REACTIVITY 

 TO VARIOUS MICROORGANISMS 



FOLLOWING the basic experiments just described, attempts 

 were made, ^vith \arying degrees ot success, to obtain the 

 actixe principles of the phenomenon from a large number of 

 microorganisms. Whilst some bacteria yielded, under simple 

 conditions of cultivation, principles endowed with high skin- 

 preparatory and reacting potencies, others prodticed the prin- 

 ciples in \o\v and variable concentrations. In order to demon- 

 strate the active principles in the latter group, it x\as necessary 

 to take advantage of the non-specificity of the phenomenon 

 and combine the intradermal injection of preparations of prede- 

 termined high potency xvith intravenous injections of prepara- 

 tions of bacteria imder investigation. Some groups of organisms 

 failed to elicit the phenomenon in spite of repeated attempts. As 

 will ])e seen from a later chapter, the knowledge concerning the 

 piiysico-chemical properties of the active principles still remains 

 meager. It may be achisable to postpone the experiments with 

 these microorganisms for the time when more information is ac- 

 ciunulated concerning the natine of the acti\e principles. 



ACTIVE PRINCIPLES OF MENINGOCOCCI S 



In attempts to reproduce the phenomenon \vith meningococcus 

 culture filtrates a great variety of fluid cultines were first used. 

 Media consisted of various combinations of tryptic digest broth 

 with glucose, whole blood, blood sertim and ascitic fluid and also 

 of combinations of plain broth of various pH xvith glucose, 

 whole blood, blood serum and ascitic fluid. The period of inctiba- 

 tion varied from one to seven days. The cultures were subjected 

 to alternating freezings and tha^vings rej^eated at frequent inter- 

 vals of time. Materials obtained in this manner were titrated for 

 skin-preparatory potency. It xvas found that the filtrates were 

 caj)able of eliciting the state of reacti\ity proxided a dilution 

 not higher than 1:6 or 1:8 was used for skin preparation and as 



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