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The McArthur microscope—Open University model
438
LABORATORY MEETING
large rubber stopper; the stopper is secured in a burette clamp; the clamped syringe is secured by a further clamp to a metal stand. A microscope slide is placed on the Perspex turntable and the end of the needle is positioned over the slide about 1 mm. above the slide. Equal parts of Araldite resin No. 1 and No. 2 are placed in a screw-cap (Bijou) bottle containing four or five pieces of metal rod (or small brass nuts), and an equal amount of acetone is added to the resin. T h e bottle cap is tightly secured and the bottle is shaken until the resin glue has mixed with the acetone to form a viscous fluid. Th e mixture is then pipetted into the top end of the syringe, and the rubber teat is pulled over the syringe barrel. The area to be marked is placed in position by adjusting the turn-table over the end of the syringe needle and the record turn-table is spun by a flick of the finger. Th e tip of the needle is lightly pressed against the rotating slide and the rubber teat is gently squeezed so as to expel sufficient fluid to make a neat circle. When the circle is completed, the needle is released and the marked slide is removed. If more than one circle is to be made on the same slide, the slide is marked beforehand with small dots (made with a nylon tipped pen) and then moved from one dot to another on the turntable until the required number of circles has been made. T h e slides should be allowed to dry for at least 24 hours before being washed in detergent followed by a good rinse with clean tap-water, after which they are ready for use. To make the resin-glue circles more visible the dry slides may be placed for one hour in 0.5% watery solution of Evans blue (heated to 50-60°C.). Slides prepared in this way are impervious to detergents, acids and other solvents, and the resin does not chip off even after prolonged use. These marked slides are particularly suitable for immunofluorescence tests by micro-techniques in that the marked areas are clearly defined and may with ease be adjusted to any size, thus enabling several tests to be carried out on a single slide with little danger of overspill from one well to another. REFERENCE CAMARGO, M. E. (1965).
Revta Inst. Med. trop. S~o Paulo, 7, 39.
The McArthur microscope--Open University model J. M c A R T H U R This is a revised and moulded model of the standard McArthur microscope. It was conceived initially for rural tropical medical work, but with schools also in view, and the sudden demand for 8,000 microscopes by the Open University has pressed this design forward. Th e instrument measures 5 x 3 x 1 inches and weighs 8 ounces. It has overall magnifications of 80 ~" and 200 x, provides automatic focusing, polarizing, measurement and counting, the examination of sediments in considerable volumes of fluid, and both external and battery operated illumination. Th e tender for this order was won against conventional microscopes made by manufacturers from all over Europe, and the development of this instrument from an idea to actual delivery within nine months culminating in 450 instruments a day, must constitute something of a world record in microscope production. This microscope will shortly be on the open market.
LABORATORY MEETING
large rubber stopper; the stopper is secured in a burette clamp; the clamped syringe is secured by a further clamp to a metal stand. A microscope slide is placed on the Perspex turntable and the end of the needle is positioned over the slide about 1 mm. above the slide. Equal parts of Araldite resin No. 1 and No. 2 are placed in a screw-cap (Bijou) bottle containing four or five pieces of metal rod (or small brass nuts), and an equal amount of acetone is added to the resin. T h e bottle cap is tightly secured and the bottle is shaken until the resin glue has mixed with the acetone to form a viscous fluid. Th e mixture is then pipetted into the top end of the syringe, and the rubber teat is pulled over the syringe barrel. The area to be marked is placed in position by adjusting the turn-table over the end of the syringe needle and the record turn-table is spun by a flick of the finger. Th e tip of the needle is lightly pressed against the rotating slide and the rubber teat is gently squeezed so as to expel sufficient fluid to make a neat circle. When the circle is completed, the needle is released and the marked slide is removed. If more than one circle is to be made on the same slide, the slide is marked beforehand with small dots (made with a nylon tipped pen) and then moved from one dot to another on the turntable until the required number of circles has been made. T h e slides should be allowed to dry for at least 24 hours before being washed in detergent followed by a good rinse with clean tap-water, after which they are ready for use. To make the resin-glue circles more visible the dry slides may be placed for one hour in 0.5% watery solution of Evans blue (heated to 50-60°C.). Slides prepared in this way are impervious to detergents, acids and other solvents, and the resin does not chip off even after prolonged use. These marked slides are particularly suitable for immunofluorescence tests by micro-techniques in that the marked areas are clearly defined and may with ease be adjusted to any size, thus enabling several tests to be carried out on a single slide with little danger of overspill from one well to another. REFERENCE CAMARGO, M. E. (1965).
Revta Inst. Med. trop. S~o Paulo, 7, 39.
The McArthur microscope--Open University model J. M c A R T H U R This is a revised and moulded model of the standard McArthur microscope. It was conceived initially for rural tropical medical work, but with schools also in view, and the sudden demand for 8,000 microscopes by the Open University has pressed this design forward. Th e instrument measures 5 x 3 x 1 inches and weighs 8 ounces. It has overall magnifications of 80 ~" and 200 x, provides automatic focusing, polarizing, measurement and counting, the examination of sediments in considerable volumes of fluid, and both external and battery operated illumination. Th e tender for this order was won against conventional microscopes made by manufacturers from all over Europe, and the development of this instrument from an idea to actual delivery within nine months culminating in 450 instruments a day, must constitute something of a world record in microscope production. This microscope will shortly be on the open market.