86 MICRO-ORGANISMS AND DISEASE [chap. 



sterile fluid, salt solution, or distilled water, and then plate- 

 cultivations in gelatine or Agar are made with definite 

 quantities of the distribution. 



{b) To determine the general character of the microbes, 

 the colonies in the gelatine or Agar plates are subjected to a 

 close study in microscopic specimens and in subculture. 

 For determining the presence of bacillus coli, bacillus of 

 typhoid, the sewage variety of proteus Zenkeri, particles of 

 the solid matter are inoculated into melted phenol gelatine 

 or phenol broth and then proceeded with as in the case 

 of water. For detection of the diphtheria bacilli see the 

 chapter on diagnosis of diphtheria. 



For the diagnosis of the cholera vibrio, particles of the 

 material are inoculated into tubes containing i per cent, of 

 peptone and I per cent, salt, incubated at 37° C. for twelve 

 to twenty-four hours and examined in the same way as 

 mentioned of water. 



Methods of Anaerobic Cultivation . — If it is required to grow 

 and isolate bacteria which cannot grow or only very slowly and 

 feebly in free air, it is necessary to make anaerobic cultures. 

 Various methods and modifications have been designed for 

 this purpose, but I have found in actual practice that all those 

 species which have hitherto been described can be grown in 

 the depth of grape sugar gelatine (at 20° C.) or in grape sugar 

 broth or gra'pe sugar Agar (at 37° C), without any difficulty. 

 A test-tube containing to two-thirds its height the solid sugar 

 gelatine or solid sugar Agar, or fluid sugar broth, is easily in- 

 oculated in the deeper parts — / e,, that nearer the bottom than 

 the surface of the tube — by means of a capillary pipette con- 

 taining the bacteria in fluid suspension, the pipette being 

 well pushed down into the medium and a droplet pressed 

 out by blowing. The tube is then sealed up with tissue 

 paper or paraffin or indiarubber. 



