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PATHOGENIC MICROORGANISMS 



The patient is required to wash out his mouth with some antiseptic, 

 and then expectorate sputum obtained by coughing, into a Petri dish. 

 The sputum is washed by lifting it through a series of watch glasses 

 containing sterile salt solution and is then ground in a mortar with a 

 little salt solution, and the even emulsion so obtained is injected intra- 

 peritoneally into a white mouse. A fine needle is carefully introduced 

 upward and inward from just above Poupart's ligament. Puncture 

 of the liver may be avoided in this way. The pneumococci develop in 

 the peritoneum, and after 4 to 8 hours the mouse is killed and the peri- 

 toneal cavity carefully washed with salt solution by means of a capillary 

 pipette. The washings are placed in a centrifuge tube at low speed for 

 several minutes to bring down leucocytes. The supernatant fluid is 

 then centrifugalized at high speed and the pneumococci so obtained are 

 resuspended in salt solution. This suspension is then added to equal 

 parts of the sera of Types I and II in dilutions of 1 : 2 . 5 and 1:10, with, 

 of course, proper controls and a bile test to determine bile solubility. 

 Agglutinations can also be made later with broth cultures made from 

 the mouse's heart's blood or peritoneal exudate. 



Protection experiments for similar determinations can be carried 

 out by the method shown in the following protocol taken from the work 

 of Dochez and Avery: 



(The quantities in c.c. representing dose of culture refer to young 

 broth cultures.) 



