46 BACTERIOLOGY. 



tion to minute technical details, will surely be 

 followed with disappointing results in the contami- 

 nation of one's cultures, resulting in the loss of 

 much time. When using platinum needles, either 

 for inoculating fresh tubes in carrying on a series 

 of pure cultures, or in transferring a small portion 

 of a cultivation to a cover-glass for examination 

 under the microscope, the careful sterilisation of 

 the needle by heating the platinum wire till it is 

 white hot in every part, and heating also as much 

 of the glass rod as is made to enter the test- 

 tube, must be carried out with scrupulous care. 

 Indeed it is a good plan to let it become a 

 force of habit to sterilise the needle before and 

 after use on every occasion, whatever may be the 

 purposes for \vhich it is employed. 



(A) EXAMINATION IN THE FRESH STATE. 



Liquids containing micro-organisms such as 

 pus, blood, juices, culture-fluids, can be investigated 

 by transferring a drop with a sterilised ose or a 

 capillary pipette to a slide, covering it with a 

 clean cover-glass, and examining without further 

 treatment. If it is desirable to keep the specimen 

 under prolonged observation, a drop of sterilised 

 water or salt solution must be run in at the 

 margin of the cover-glass to counteract the 

 tendency to dry. Cultures on solid media can be 

 examined by transferring a small portion with a 



