Blood and Urine during Lobar Pneumonia. 127 



infected animals. However, it has been found both when pneumo- 

 cocci were present in the circulating blood and when, by blood 

 culture, organisms were absent. Complement fixation, as well 

 as the precipitin reaction, may be used for the demonstration of 

 this substance in serum. 



The fact that considerable quantities of soluble material formed 

 by the pneumococcus are present in the circulating blood in infec- 

 tion suggested the likelihood of its excretion in demonstrable 

 form in the urine. Study of the urine by precipitin reactions in 

 animals experimentally infected with pneumococcus and in a 

 large series of individuals with lobar pneumonia showed a speci- 

 fically precipitable substance to be present in almost every instance 

 during some stage of the disease. A positive reaction has been 

 found as early as twelve hours after the initial chill, and has been 

 demonstrated in one instance five weeks after defervescence of 

 fever. The reaction in different urines may vary from a faint 

 cloud to a heavy precipitate. In certain instances the reaction 

 may be negative when whole urine is used but become positive 

 by chemical concentration of the substance in the same urine. 



A study of the chemical nature, toxicity, antigenic properties 

 and fate of the soluble substance in normal and infected animals 

 is still in progress. The following facts, however, have already 

 been ascertained concerning its chemical nature. The specific 

 substance is not destroyed by boiling. It is readily soluble in 

 water, precipitable in acetone, alcohol and ether. It is pre- 

 cipitated by colloidal iron and does not dialyze through parch- 

 ment. Its immunological reactions are unaffected by proteolytic 

 digestion with trypsin and the substance is not split by urease. 

 The determination of total nitrogen and nitrogen partition on the 

 active substance obtained by repeated precipitation with acetone 

 and alcohol, shows this substance to be of protein nature or to be 

 associated with protein. 



