156 



PURE CULTURES FROM PATHOLOGIC MATERIAL 



FIG. 78 



method gives good results in obtaining pure cultures of the tetanus 

 bacillus. 



The other method of Wright's is as follows: The apparatus 

 consists of a simple arrangement of glass and rubber tubes enclosed 

 in an ordinary test-tube with a plug or cotton inserted in its mouth, 

 as in an ordinary culture tube. The construction of the apparatus 

 is shown in Fig. 78. A is a glass tube, somewhat constricted at each 



extremity. B and C are short pieces of small 

 rubber tubing. D is a glass tube, in the 

 upper extremity of which a small plug of 

 cotton is inserted; E is a piece of rubber 

 tubing. The test-tube contains a quantity 

 of the fluid culture medium. When it is 

 desired to make an anaerobic culture the 

 fluid in the test-tube is inoculated in the 

 usual way. The fluid is then sucked up into 

 the system of glass and rubber tubes to a 

 level above the rubber tube C. W T hen it 

 has reached this level the rubber tube E is 

 compressed between the fingers to prevent 

 the down flow of the fluid, and the system 

 of tubes is then pushed downward in such a 

 way as to bend the rubber tubes B and C as 

 shown in Fig. 78. If the test-tube and the 

 inner-tube system are of suitable size the 

 rubber tubes mentioned will remain in this 

 bent position. The fluid in the tube A is 

 thus contained in a water-tight space, because 

 the rubber tubes B and C, when bent to the 

 angle shown in Fig. 78, are closed water- 

 tight. Cover-glass preparations may be 

 made from the culture fluid by straight- 

 ening out the system of tubes and allowing 

 the fluid in them to flow into the test-tube, 

 where it is accessible to the platinum loop 

 in the usual way. In using this method 

 Wright's method of making ft f course nece ssary that most of the 



anaerobic cultures in fluid . .' . J 



media. (Maiiory and Wright.) air in the culture fluid be expelled betorc it 



is inoculated. This is easily done by boiling 



the culture fluid over the flame of a Bunsen burner without removing 

 the inner system of tubes, and then cooling the apparatus by placing 

 it in cold water. 



Incubators or Thermostats. Most pathogenic bacteria grow best at 

 the temperature of the body of susceptible animals, and it is, therefore, 

 necessary to raise artificial cultures in the incubator, thermostat, or 

 brood oven at a temperature of about 37 to 38 C. Modern incu- 

 bators for bacteriologic work are generally constructed of copper, 



