22 BIOLOGY OF PNEUMOCOCCUS 



this observation naturally led the authors to test the curative 

 value of the serum of actively immunized rabbits. The direct in- 

 jection of such serums into the blood stream of the rabbit was ef- 

 fective against a lethal dose of pneumococci injected twenty-four 

 hours later. 



The Klemperers presented an array of new facts which, disre- 

 garding certain misinterpretations, have withstood the test of time 

 and supply a rational basis for the treatment of human beings with 

 immune serum. They observed that the serum of pneumonia pa- 

 tients after crisis conferred protection upon rabbits, that the pro- 

 tective substance came into action at the beginning of crisis, and 

 that it neutralized the harmful properties of Pneumococcus with- 

 out destroying the antigenicity of the organism. Having tested the 

 harmlessness of immune serum on themselves, they treated six 

 pneumonia patients with subcutaneous injections of only four to 

 six cubic centimeters, obtaining a fall of temperature within six to 

 twelve hours after injection, the temperature in two cases remain- 

 ing normal. The Klemperers sought to explain the action of serum 

 on an antitoxic basis, but in the light of our present knowledge it 

 would seem doubtful if the effect was a specific one. 



From bacteria-free bouillon cultures of virulent organisms, by 

 repeated alcohol precipitation and re-solution of the precipitate in 

 water, they isolated a protein substance, thought by them to be a 

 pneumotoxin, which was poisonous for rabbits, withstood a tem- 

 perature of 60°,* and in proper doses was capable of raising the 

 resistance of the animals above the normal threshold of infection. 

 In the blood of the immune animals they detected a substance not 

 there previously, which it was conjectured must have been formed 

 in the interval between the act of injection and the appearance of 

 immunity, and which must be dependent upon the action of the in- 

 jected albumen. The newly found substance in blood had no killing 

 effect on living pneumococci but inhibited their toxic action. In an 



* Throughout this text the figures given for temperatures represent degrees 

 on the Centigrade scale, and the initial "C" will be omitted. 



