CHAPTER V 



CULTIVATION AND IDENTIFICATION OF BACTERIA 



General Laboratory Rules. A jar containing 1 in 20 carbolic 

 acid solution should be always at hand in which to place all glass- 

 ware that has been used for infective material; after several 

 hours such articles may be cleansed by boiling in soapsuds. Old 

 used cultures may be sterilized in the Arnold for three or four hours 

 or for a shorter period in the autoclave. It is well to have within 

 easy reach a basin of mercuric chloride 1 in 1000 or carbolic acid 

 1 in 40 in which the worker's hands may be disinfected in case of 

 accidental contamination. Any infective material spilled on the 

 table should be covered with carbolic solution and carefully wiped 

 off with cotton held by forceps. Unnecessary movement in the 

 laboratory should be avoided in order that the air may be kept as 

 quiet as possible. Hands should always be 

 well washed before leaving the laboratory and 

 food should not be eaten there. Labels should 

 never be moistened with the tongue and 

 nothing should be placed in the mouth that 

 has touched any surface in the laboratory. 



Cultivation of Microorganisms. In order 

 to learn the special characteristics of an or- 

 ganism it must be studied apart from all 

 other forms on artificial culture media such as 

 already described. A large surface for growth 

 is obtained by filling tubes with solid media 

 such as agar or gelatin about one sixth full, and 

 after sterilization, while still liquid, placing 

 them in a slanting position so that when solidified they will give an 

 oblique surface of three to four inches (Fig. 15). Care should be 

 taken that the medium does not extend to the cotton plug. 



51 



FIG 



15. A. Tubed 

 Agar for Stab Cul- 

 ture. B. Agar Slant. 



