Immune Serum 505 



which reference has been made in the section upon Strepto- 

 coccus pyogenes. 



A second important method, and one that not only 

 differentiates the pneumococcus from the streptococcus, but 

 from the common organisms of similar morphology that 

 infect the mouth, is the inulin-serum water fermentation 

 test of Hiss.* In using this medium, Ruedigerf found it 

 best prepared as follows: Dissolve 5 gm. of NaCl, 20 

 gm. of Witte's peptone, and 20 gm. of pure inulin in 1000 

 c.c. of distilled water. Add 20 c.c. of a 5 per cent, solu- 

 tion of pure litmus, and tube, putting 2 c.c. of the mixture 

 into each tube, and sterilize in the autoclave. After steril- 

 ization add (with a sterile pipet) 2 c.c. of sterile, heated 

 ascitic fluid, or, preferably, heated beef-serum, to each tube, 

 and incubate twenty-four hours before using. Great care 

 must be taken not to use ascitic fluid that contains ferment- 

 able carbohydrates. Each lot must be tested with some 

 strongly fermentative bacterium, and the absence of ferment- 

 able carbohydrates proved. Ruediger prefers this prepa- 

 ration to the original solution of Hiss because he found that 

 some pneumococci would not grow on the latter. Fermenta- 

 tion of the inulin is regarded as characteristic of the pneumo- 

 coccus. 



The pneumococcus produces red colonies upon litmus- 

 inulin-agar plates, which makes their use desirable when 

 pneumococci are to be isolated from saliva, throat secretions, 

 or other material in which similar appearing organisms 

 are apt to occur. Ruediger found no other mouth bacteria 

 that produced red colonies on these plates. 



Immunity. Pneumonia is peculiar in that recovery is 

 followed by immunity of such brief duration as to permit 

 the occurrence of frequent relapses; and it is well known 

 that many cases show a subsequent predisposition to fresh 

 attacks of the disease. 



Immune Serum. G. and F. Klemperert have shown 

 that the serum of rabbits immunized against the pneumo- 

 coccus protects animals infected with virulent cultures. 

 When applied to human medicine, the serum failed to 

 do good. 



The treatment of pneumonia by the injection of blood- 



* "Jour. Amer. Med. Assoc.," 1906, vol. XLVII, p. 1171. 



t "Jour, of Exp. Med.," 1905, vol. vi, p. 317. 



J "Berliner klin. Wochenschrift," 1891, Nos. 34 and 35. 



