D. Ghosh Antibiotics Research Centre, Pimpri lNeor Poona), India
Device for Pipetting Pathogenic Organisms
With an ordinary Pyrex test tube (100 X 13 mm) and two short pieces (about 15 mm and 10 mm) of rubber tubing of suitable diameter to fit the test tuba snugly and of bore size same as the outside diameter of pipet, a very simple suction device can be made for pipetting strong acids, alkalies, KCN solutions, and suspensions of pathogenic bacteria and fungi. A small hole is conveniently made a t the bottom of the test tube by first
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Journal of Chemical Education
grinding a little with a flat file and then sharply ha.mmering a pointed needle from inside after holding the test tube in u .~ r iz h ~osition t. over a hole in a rubber cork. With a little care the hole could be made quite uniform and could be conveniently closed by the forefinger as in an ordinary pipetting operation. The smaller piece of rubber tube is then pushed down to the bottom of the tube (to prevent pipet from hitting the bottom of the test tube) and the larger piece fitted at the mouth. The suction end of the pipet is introduced into the test tube through the rubber tube (see figure). By holding the pipet with the left hand and moving the test tube up with the right hand keeping the hole closed with forefinger, the liquid to be pipetted can be sucked in and delivered as usual. A little lubrication will greatly facilitate the movement of the test tube.
