<span>Anton van Leeuwenhoek learned to grind lenses ( 1668) and develop simple microscopes.
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Leeuwenhoek heated the middle of a small soda glass rod , over a flame. On pulling apart the two ends, the glass rod elongated into thin whiskers .
Heating the end of this whisker resulted in a tiny high quality glass sphere. These glass spheres then became the lens of his microscope, with the smallest sphere providing the greatest magnification.
Leeuwenhoek's designs were very basic. The body of the microscope was a single lens mounted in a tiny hole on a brass plate. The specimen was then mounted on a sharp point that sticks up in front of the lens. It's position and focus could be adjusted by turning the two screws.
The entire instrument was about 3 to 4 inches long and had to be held up close to the eye, requiring good lighting and great patience to use.
Answer:
cold with high salt content
The nurse should obtain the specimen from the catheter.
One of the tests from urinalysis that frequently got contaminated is about infection. The area near the orificium of uretra is near the skin, so there will be microbes around it that can contaminate the sample. The contaminated sample will give a false positive and the result will show the urine are infected.
Taking the specimen from catheter will prevent that contamination, thus giving a better sample.
