GONOCOCCUS. 261 



The method used by Pfeiffer for the cultivation of 

 the bacillus of influenza is also said to have been suc- 

 cessfully employed. Abel recommends a needle-prick 

 in the finger as a most convenient source from which to 

 obtain the necessary amount of human blood that is to 

 be smeared over the surface of the slanting agar-agar 

 when Pfeiffer's method is employed. 



Wright's modification of Steinschneider's method has 

 given such satisfactory results in his hands that it will 

 be given here with more or less detail. The medium 

 consists of a mixture of urine, blood-serum (human or 

 bovine, either serving the purpose), and nutrient agar- 

 agar. The urine and blood-serum are collected with- 

 out special aseptic precautions, and subsequently freed 

 from bacteria by filtration through unglazed porcelain. 

 Frequently this is the tedious part of the process, as 

 the serum and urine pass very slowly through the por- 

 celain filters that are generally employed in laborato- 

 ries. Wright recommends a filtering cylinder manu- 

 factured by the Boston Filter Company as an apparatus 

 that not only strains out all bacteria, but also permits of 

 a very rapid passage of the fluid. 



The details of the method as given by Wright are as 

 follows: "A litre of nutrient agar is prepared in the 

 usual manner, and after filtration it is evaporated to 

 about 600 c.c. This concentration is desirable, so that, 

 after the dilution with the urine and serum, the medium 

 may be sufficiently firm. This concentrated agar is then 

 run into test-tubes and the whole sterilized by steam on 

 three successive days. The quantity of agar placed in 

 each tube is smaller than is usual; this is in order to 

 allow for the subsequent addition of the urine and 

 serum. 



12* 



