264 



BACTERIOLOGY. 



Fig". 42 is made use of. This apparatus can be readily im- 

 provised out of an ordinary 250 c.c. measuring- cylinder. 



Usually, bouillon cultures are employed for the pur- 

 pose of injection. Occasionally, however, the bacterial 

 growth is on a solid medium, like ag-ar or potato. In that 

 case, bouillon or sterile water should be introduced into the 

 tube by means of a drawn out tube pipette (Fig-. 61). The 



growth is then thoroug-hly 

 stirred up in the liquid by 

 means of the end of the 

 pipette. The suspension is 

 then drawn up into the tube, 

 and transferred to a sterile 

 Esmarch dish, or to a small 

 sterile conical test-glass (Fig-. 

 43). In the case of a bouillon 

 culture, this is transferred 

 directly to the sterile vessel. 

 The neck of the tube, after 

 withdrawal of the cotton 



FIG. 42. Apparatus for injecting large quantities of liquid. 



plug-, must, of course, be heated in the flame before pouring- 

 out the culture. 



When injecting- small animals care must be taken that 

 the needle does not pass throug-h the abdominal wall into 

 the peritoneal cavity. A fold of the skin should be raised, 

 and the needle inserted while the syring-e is held in a 

 position almost parallel to that of the body. A success- 

 ful subcutaneous injection will show a swelling- over the 

 place of inoculation. 



The injection is made most conveniently over the abdominal 

 wall, inasmuch as the skin is softer there than elsewhere. The rabbit 



