Immunization against Cyanolophia. 161 



application of serum No. 65 and brain No. Q, and several days later 

 serum No. 65 and brain No. 15 together with control animal O2. 

 I lost chickens 96 and 99 and 0 2 . So I kept 8 immune chickens, 

 because I used four of them for experiments which I cannot 

 record here. Chickens 30, 31, 32, 33, 40, 65, 80 and 81 remained, 

 and passive immunity could be easily produced by using, for 

 example, the serum of either 40 or 65. Both sera applied to un- 

 treated chickens together with virulent brain No. 21 or No. 15 

 protected them fully. One chicken four weeks after its first 

 treatment with serum 65 and brain No. 21 was not killed by a 

 renewed application of brain No. 21. So at least the passive 

 immunity lasted four weeks. I could not follow my experiments 

 to an end because I was compelled by circumstances beyond my 

 control to kill the immune chickens on the 23rd of April, 191 7. 

 This causes me to publish my results as they are : 



They prove that it is possible to raise the resistance against 

 Cyanolophia by slow degrees in applying to the animals the 

 attenuated virus. But, and that seems important, the virus 

 must occur in different physiological stages in the body, as already 

 von Prowazeck believed, and the animal has to be protected 

 against all these possible stages of the agent. The form of the 

 agent in serum, in brain and liver tissue and that form which 

 appears when virulent brain and liver tissue or serum is attenuated 

 with embryonic tissue, must be physiologically different, and it 

 seems only logical to immunize against each of these supposed 

 forms. 



References. 



1. Maggiora & Valenti. Zeitschr.f. Hyg. u. Inf., Bd. 42. 



2. von Prowazek. Munch, tned. Wochenschr., Jahrg., 55. 



3. Kraus & Schiffmann. Cenlralbl. f. Bakt., Abt. I, Orig. Bd. 43. 



4. Kraus & Doerr. Cenlralbl. f. Bakt., Abt. I, Orig. Bd. 46. 



5. Kraus & Loewy. Cenlralbl. f. Bakt., Abt. I, Orig. Bd. 76. 



6. Erdmann. Proc. of Soc. Exp. Biol, and Med., Vol. 13. 



