352 BACTERIOLYSINS 



7. 1 c.c. of the patient's serum in dilution of 1 : 100 -f- 0.5 c.c. cul- 



ture + 0.5 c.c. bouillon. A control on the possible presence of 

 complement in this serum. 



8. 1 c.c. of the control serum in dilution of 1 : 100 + 0.5 c.c. culture 



+ 0.5 c.c. bouillon. A control on the possible presence of 

 complement. 



All tubes with the exception of the first control which has been plated 

 are placed in an incubator at 37 C. for three hours. At the end of this 

 time the contents of each tube are plated in neutral agar. Sterile Petri 

 dishes should be properly and plainly labeled with a wax-pencil and 

 arranged in order. A flask of plain neutral agar is melted in boiling 

 water and cooled to 42 C. The tubes are removed from the incubator 

 and shaken gently and with the aid of an assistant from 5 to 8 c.c. of 

 agar are added carefully to each tube with a sterile 10 c.c. pipet. The 

 contents are mixed by gentle rotation of the tube and then poured in the 

 corresponding Petri dish, followed by an additional mixing according to 

 the usual bacteriologic procedure. With ordinary speed the whole set 

 of tubes may be poured in a satisfactory manner before the flask of agar 

 has had time to harden. 



Another method of plating consists in pipeting the contents of each 

 tube into its corresponding dish, and then washing the tube with an 

 additional 1 c.c. of sterile salt solution, to remove all traces of serum and 

 culture. Or the end of each tube may be flamed and the contents 

 poured directly into a dish. If this method is adopted, small test-tubes 

 should be used. While the method is more convenient, it is usually not 

 so accurate as the first two methods. 



Neisser plates but 5 or 10 drops from each tube. The dose decided 

 upon is the one employed throughout. For example, it would be erro- 

 neous to take 5 drops from one tube and 10 from another. Neisser, 

 however, uses much smaller amounts of the serum, as 1, 0.3, 0.1, 0.03, 

 and 0.01 c.c., instead of the much higher dilutions given in this technic. 

 These differences must be remembered and the proper dilutions employed, 

 and but 5 to 10 drops should be plated in performing the bactericidal 

 plate test according to Neisser's technic. 



Topfer and Jaffe pour a thin layer of agar into a Petri dish and allow 

 it to harden. Upon this they pour the culture-serum agar mixture, 

 which, after settling, is covered with another thin layer of agar. In 

 this way a culture in the water of condensation is avoided. In the usual 

 technic this may be avoided by turning the plates over soon after harden- 

 ing occurs so that the water of condensation collects on the cover. 



