Figure 2: Cheek smear at 40x magnification
Figure 3: Onion root tip at 40x magnification
The discovery of the microscope opened an entire new world to the realm of science. It allowed objects within reach that seemed completely non-existent. And today, it is a very important tool for many biologists in discovering new organisms like the cell and DNA, diseases, and medication formulations. The first microscope was founded by the father and son glass eye makers Hans and Zacharias Janssen around the year 1595. It was a basic tube with lens scopes at each end ranging from 3x magnification to 9x magnification. Another pioneer of the microscope discovery was Robert Hooke. He contained a vast knowledge of math, chemistry, physics, and engineering, which provided him with the stepping stones to many of his inventions, including the improvement of the early compound microscope. In 1665, he discovered the features of a plant tissue from the magnification of cork from the bark of an oak tree. He wrote his observations and inquiries in his book Micrographia. Today, the compound light microscope is a complex tool that contains several different parts that enhances the quality of the magnified subject.
One of the major parts of the compound light microscope are the ocular lenses. These lenses allow the visual of the subject through two oculars and enhance the specimen at 10x magnification. In order to see the specimen properly, one must move the oculars left or right, while looking through the lenses, in order to see the subject. In relation to the ocular lenses, the objective lenses, which are positioned above the specimen being viewed, also enhance the image at 4x, 10x, 40x, and 100x magnification and is multiplied with the ocular lenses power to give the total magnification of the microscope. These objective lenses should always start at 4x magnification and changed while looking at the microscope. The stage is also another major part of the microscope, because it is a platform for placement of the slide of the subject. This part can be adjusted up and down by the coarse adjustment knob. The stage should always start at its lowest point before the slide being studied is placed upon it. The coarse adjustment knob, as mentioned above, allows for quick focusing by moving the stage and is used for overall focusing of the specimen. It is best to change this knob while looking through the microscope. Along with the coarse adjustment knob, is the fine adjustment knob, which is a slow control used to fine focus the image at higher magnifications like 40x, as displayed in figure one and two. It is also better to change this knob while through the microscope. And finally, located underneath the stage, is the iris diaphragm control. This is a lever that adjusts the amount of light illuminating the slide. And it is better to change this knob while looking through the microscope. Although the microscope may appear to be very complex, from the online microscope simulator, it is quite simple to experience and understand the microscope.
On the online microscope simulator, I first chose the slide of the cheek smear. I turned on the microscope, changed the rheo stat to 10, put the 4x objective lens into place, centered the specimen, started the stage at top position by moving the coarse adjustment knob, switched views to make seem like I was looking through the microscope, adjusted the oculars by moving the eyepieces to the right, moved the coarse adjustment knob to find the slide and once I did I used the fine focus knob to see the fine detail. Then I switched the objective lens to 40x magnification, which really enhanced the image, displaying the cheek cells. Lastly, I adjusted the iris diaphragm to see the cheek cells in a better illumination. I followed the same steps for the onion root tip.
The microscope has become and always will be an essential tool to all sciences, especially biology. It is from its discovery by Hans and Zacharias Janssen and Robert Hooke that scientists have been able to discover many things like the cell and DNA. Today, the microscope has many complex features like the ocular lenses, objective lenses, stage, coarse and fine adjustment knobs, and the iris diaphragm control that enhances the quality of the specimen being viewed. During the online microscope simulator, I was able to look at a cheek smear and an onion root tip at a 40x magnification. I was able to get an understanding of the purpose of the microscope and see what seemed non-existent. It is from the discoveries of the past that people in the present have a better chance to understand the very complexities of life.
Sources: www.udel.edu/biology/ketcham/microscope
www.southwestschools.org/jsfaculty/Microscopes/fathers.html
The Microscope: Biology 181 Lab
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