LIVING, UNSTAINED 75 



( intended to destroy any micro-organisms that 

 may have become entangled in the loose fibres 

 of the cotton-wool, and which, if not thus de- 

 stroyed, might fall into the tube when the plug 

 is removed and so accidentally contaminate the 

 cultivation.) 



3 . Hold the tube at or near its centre between 

 the ends of the thumb and first two ringers of 

 the left hand, and allow the sealed end to rest 

 upon the back of the hand between the thumb 

 and forefinger, the plug pointing to the right. 

 Keep the tube as nearly in the horizontal posi- 

 tion as is consistent with safety, to diminish 

 the risk of the accidental entry of organisms 

 (Fig. 68). 



4. Take the handle of the loop between the 

 thumb and forefinger of the right hand, holding 

 the instrument in a position similar to that 

 occupied by a pen or a paint-brush, and sterilise 

 the platinum portion by holding it in the flame 

 of a Bunsen burner until it is red hot. Sterilise 

 the adjacent portion of the aluminium handle 

 by passing it rapidly twice or thrice through 

 the flame. After sterilising it, the loop must 

 not be allowed to leave the hand or to touch 

 against anything but the material it is intended 

 to examine, until it is finished with and has been 

 again sterilised. 



5. Grasp the cotton-wool plug of the test- 

 tube between the little finger and the palm of 

 the right hand (whilst still holding the loop as 

 directed in step 4), and remove it from the 

 mouth of the tube by a " sere wing" motion of 

 the right hand. 



6. Introduce the platinum loop into the tube 

 and hold it in this position until satisfied that 



i it is quite cool. (The cooling may be hastened 



