Word: fluorescein
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Into this mixture the multivator will squirt a shot of test chemicals-fluorescein spiked with phosphate. The fluorescein cannot give off its telltale glow until the phosphate has been removed, and nothing can remove phosphate better than the enzyme phosphatase, which is common to all life on earth...
First, a drop of the specimen fluid is smeared on a microscope slide. Then it is covered with a drop of serum (from an animal) containing the antibody which develops when the suspected species of bacteria is present. This serum is tagged with fluorescein, a luminous substance. If the right antibody hits the right germ, the germ starts to glow under the microscope. If the tester has guessed wrong, no glow, and he tries again with other antibodies...
...Kurt Lange and David Weiner of the New York Medical College got the idea while studying blood circulation by means of fluorescein, a tracer dye which, injected into the blood, flows freely with it and glows yellow-green under long-wave ultraviolet light. When they froze rabbit tissues (and later that of human volunteers) they found that after a time the whole frozen area glowed brightly, indicating blood concentration...
When the doctors have a patient with a gangrenous foot or strangulated hernia (protruding loop of gut), they wheel him into an operating room, inject fluorescein, a reddish dye, into the vein of his arm. Then they darken the room, shine an ultraviolet lamp on the gangrenous area. The dye should make a circuit of the patient's blood stream in 20 seconds. If the gut or foot is still alive and receiving fresh blood, it will glow yellow green. Then it is safe to tuck the gut back in place, or stimulate circulation...
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