REACTIVITY TO VARIOUS MICROORGANISMS 37 



pletely lost its activity. A number of repeated attempts to obtain 

 active preparations from this strain for a jjeriod of six montlis 

 made since the time this was first noticed gave only negative 

 results. These attempts included passages of the strain through 

 mice, modifications in meditmi composition hydrogen-ion con- 

 centration, etc. 



Ecker and Welch (1930), Apitz (1933^), Gerber (iggOrt), 

 Stolyhwo (1935), and others were afjle to elicit strong reactions 

 with the above described "agar washings" filtrates of B. typhosus. 



Burnet (1931) apparently obtained active preparations in cul- 

 ttnes autolyzed by the method of Besredka. 



ACTIVE PRINCIIM.ES OF B. PARATVl^HOSUS 



In early experiments the phenomenon was elicited with filtrates 

 of ctdtines of B. paidtyphusus A, B, and B. enteriditis grown in 

 tryptic digest broth for six days (Sh^vartzman, 1928a) . Amotnits 

 as large as 2 c.c. per kilo of body ^veight, ^vere used for the 

 provocative injection. Ecker and Welch (1930) obtained active 

 preparations from B. paidtyphosus A, B. aertrycke, B. enteritidis, 

 B. paratyphosus B, B. aertrycke (Nobele) , and B. paratyplwsus 

 (Schottmiiller) in the synthetic meditnn of Ecker and Rimington 

 (1927). In my recent experiments "agar \vashings" filtrates of 

 B. enteritidis isolated from a spontaneous epidemic in mice 

 yielded preparations containing ()00 to 800 reacting tuiits per 

 1 c.c. 



ACTIVE PRINCIPLES OF B. COEI 



Active principles of B. coli may be easily obtained in plain 

 broth and washings on j^lain agar ctdttires. B. coli plain broth 

 culture filtrates Avere used successfully by Gratia and Linz 

 (1932c), Ecker and Welch (1930), Duran-Reynals (1933/0' P- 

 Bordet (1936/;) , and others. 



I carried out comparative studies on plain broth and "agar 

 washings" filtrates. Plain broth cultures were incubated for three 

 days, centrifuged, and filtered through Berkefeld "V" candles. 

 Four-tenths per cent of phenol \vas added for preservation. Sev- 

 eral batches of broth culture filtrates contained bet^veen 40 to 60 

 reacting units per 1 c.c. The "agar washings" filtrates Avere made 

 from cultures on Kolle flasks containing plain agar, pH 7.4, in- 

 cubated for twenty hours. The growth of each flask ^vas ^vashed 

 off with 2-4 c.c. of phenolized saline. The filtrates thus obtained 



