66 MEDICAL BACTERIOLOGY 



gated all pneumococci that are not agglutinated by Type I or Type II serums and 

 lack the capsule, or fail, when denuded, to agglutinate with Type III serum. 



Any Type IV pneumococcus when injected into an animal will produce a 

 serum that will agglutinate cultures of the particular organism with which 

 the animal was injected but will not agglutinate other Type IV pneumococci 

 nor any other organisms. 



The evidence so far accumulated shows that Type I serum administered to 

 patients infected with Type I pneumococci and Type II serum administered to 

 patients infected with Type II pneumococci exerts a more beneficial effect on the 

 course and termination of the disease than any other therapeutic agent. An 

 effective serum for the treatment of patients infected with Type III pneumococci 

 has not been produced; the same is true of patients infected with Type IV 

 organisms. 



Type I serum has no effect on disease caused by any other organisms ; Type 

 II serum has no effect on disease caused by any other organisms; a polyvalent 

 serum that might be employed with some benefit in any case, regardless of the 

 type of pneumococcus offending, while most desirable, has not yet been produced. 



Such observations as have been made during the last 2 years seem to show 

 that the majority of cases of acute lobar pneumonia are caused by Type I or 

 Type II pneumococci; that in different localities and years there are variations 

 in the predominance of these, at one time Type I infections are more numerous 

 than Type II and vice versa; that Type IV infections constitute about 25 per cent, 

 of all cases; that Type III is the most virulent, Type II next in virulence and 

 Type IV least; that the pneumococci found in the mouth or sputum of healthy 

 and tuberculous persons, in practically all cases are Type IV organisms; and that 

 the more virulent forms are present in the sputum of convalescent patients for 

 a comparatively short time, as a rule. 



It now seems desirable to discover to which of the four types the offending 

 organism belongs in every pneumococcus infection and for this purpose a com- 

 paratively simple technique has been worked^out. 



IDENTIFICATION OF DIFFERENT TYPES OF PNEUMOCOCCI 



Wash out patient's mouth with sterile water; have patient cough up some ' 

 mucus from the throat or lungs; catch this sputum in a sterile container, put 

 about 7 cc. of it in a centrifuge tube, add an equal quantity of sterile water, 

 shake, centrifugalize at high speed for 15 minutes. Remove supernatant fluid, 

 fill tube up again with sterile water, shake, centrifugalize at high speed for 15 

 minutes, discard supernatant fluid. 



Draw the sediment into a sterile syringe and inject ^ cc. into the peritoneal 

 cavity of a mouse; from 3 to 6 hours later chloroform the mouse, inject 10 cc. 

 of normal salt solution into its peritoneal cavity (to collect the organisms that 

 have multiplied) and withdraw it again. This fluid is centrifugalized just 

 enough to free it of tissue cells. 



Place five test-tubes in a rack and put an equal quantity of the washings 

 from the mouse in each of the first three tubes none in the last two. Put 



