52 LOCAL TISSUE REACTIVITY 



inactive. Inasimu h as in the experiments with (^her microorgan- 

 isms strains l)elonging to the same serological group may differ 

 in ability to prodtice the active principles of the phenomenon, 

 other strains of pneinnococcus Type I should be tested. 



The pneumococcus reacting factors completely deteriorated in 

 some filtrates shortly after their preparation, but seemed to have 

 been preserved quite well in others for a consideral)le length of 

 time. In one preparation there ^vas observed a partial deteriora- 

 tion of reacting factors after three months storage. The variance 

 of these residts ^vas prol)al)ly due to differences in initial concen- 

 tration of the factors. 



No definite conclusions could be drawn concerning the opti- 

 mum conditions necessary for preparation of pneumococcus re- 

 acting factors, because various batches of filtrates prepared imder 

 identical conditions but at various times differed in potency. 



It appeared, however, that the use of several sugars ^vas induc- 

 ive to the development of potent factors. Observations on the 

 favorable effect of multiple sugars on the development of toxins 

 was previously made by Hagen and Heller (1931) ^vith B. dlph- 

 tJieriae. 



It may also appear difficult to determine the optinnnn length 

 of the incid^ation period. Twenty-fotu" and forty-eight hour in- 

 cubation periods seemed sufficient to obtain potent filtrates. 



The use of starch medium advocated by PagoiUatos (1931) for 

 preparation of Dick toxin proved of no special advantage. Favor- 

 able residts were obtained with "double strength" broth. The 

 mediiun ^vas successfully used by Parker and Pappenheimer 

 (1928) for the preparation of pneinnococcus sid^stances of pri- 

 mary toxicity. 



Inasmuch as the reacting factors could be obtained both anaero- 

 bically, as weW as aerobically, it became possible to differentiate 

 them from Parker and Pappenheimer's pneumococcus toxic sub- 

 stances which are strictly anaerobic. 



ACTIVE PRINCIPLES OF B. TUBERCULOSIS 



In 1932, Nasta attempted to reproduce the phenomenon of 

 local skin reactivity to B. luhcyculosis. Rabbits and guinea pigs 

 were prepared by an intradermal injection of small amounts of 

 tuberculin O. T., glycerine broth, and virulent live tubercle ba- 

 cilli. Twenty-four hours later, the rabbits received 0.5 c.c. of 

 tuberculin intravenously. The guinea pigs received smaller doses 



