36 LOCAL TISSUE REACTIVITY 



seeded each \vith 3-4 c.c. oi t\vcnty liour old plain broth cultures 

 of B. l\l)lio.sii.s diluted i:.} with o.t) }:)er cent NaCH solution. The 

 dilution is made innnediately heiore use. After twenty to twenty- 

 two horns of incid)ation the growth of each flask is Avashed off 

 \vith 2-4 c.c. of 0.9 per cent NaCl solution containing 0.4 per cent 

 j)henol. The washings are then pooled, centrifuged within the 

 following one to t\vo hotns and the clear supernatant fluid filtered 

 through Berkefeld "V" candles shortly after centrifuging. 



Numerous batches of "agar washings" filtrates of B. typhosiis 

 W'Cre titrated for reacting potency in rabbits prepared by a single 

 intradermal injection of 0.25 c.c. of midiluted filtrate, dining the 

 past six years. Most of the work Avas done ^vith a strain Tl iso- 

 lated some years ago from the stool of a typhoid fever patient. 

 The strain showed colonies on plain agar which appeared dis- 

 tinctly granular under the dry lo^v power lelis. Their margin a\ as 

 ameboid and some^vhat ragged but this ^vas not sufficiently pro- 

 nounced to classify this strain as rough. This intermediate type 

 of roughness, is however, a stable characteristic since it persisted 

 for a nimiber of years ^vithout any change either in the direction 

 of smoothness or more pronoimced roughness. The stability Avas 

 ascertained by 42 "platings" of this strain. No typical rough col- 

 onies Avere obtained from old fluid cultures. Broth cultmes 

 showed, in addition to the luiiform cloudiness, an insignificant 

 amount of precipitate Avhich on shaking gave rise to easily broken 

 up flakes. Suspensions in 0.85 per cent saline incid)ated in a Avater 

 bath at 37° c. for two hours Avere only slightly agglutinated. The 

 remaining strains of B. lypJwsus described below Avere typically 

 smooth. 



The folloAving is the range of the reacting potency of various 

 batches of filtrates derived from B. typ]wsus. Strain Tl — 100 to 

 1000 reacting units; strain 1684 — 50 to 100 reacting luiits; strain 

 1687 — 25 reacting units; strain 837 — 150 reacting units; strain 

 864 — 75 to 250 reacting luiits; strain 157 — 100 reacting units; 

 strain 240 — 400 to 600 reacting units; strain 159 — 600 to 1000 re- 

 acting units; Typhoid 0-901 (Felix) — 300 reacting imits; Ty- 

 j)h()id H-901 (Felix) — 900 reacting units. 



As may be seen from the above, under ajjparently identical 

 conditions various strains of B. typJwsus may substantially difTer 

 in their ability to produce active principles of the phenome- 

 non. The strain Tl Avhich Avas successfidly employed for produc- 

 tion of actiAe principles for a period of eight years recently com- 



