Numerous number of small inventions have made a huge difference in the human existence. Most of the vital inventors and vital inventions are not realized by many, like Petrache Poenaru who invented fountain pen, George de Mestral who invented Velcro, and many more who have massively contributed to the world by small but very efficient inventions. These small inventions have not only been the simplest of inventions (as one may think about it) but these are the devices that has helped every individual in every corner of the world.
Today, we see Google celebrating the scientist Julius Richard Petri's 160th birth anniversary with an interactive doodle of his invention, the Petri dish. The Doodle features a six colorful Petri dishes laid out in a row. A gloved hand appears when you click on the yellow dish. It stirs the dishes and in a little while, the microbes start to grow and spell out the Google letters. The dishes show bacteria present in worn socks, door knob, keyboard, pet dog, plant, and a wet sponge complete with animated images.
What is the dish?
To elaborate on the scientific utensil, a Petri dish (or Petri plate or cell culture dish) is a shallow glass or plastic cylindrical lidded dish that biologists use to culture cells or small moss plants. Glass Petri dishes can be reused by sterilization. For experiments where cross-contamination from one experiment to the next can become a problem, plastic Petri dishes are often used as disposables.
How it was invented:
The invention of the dish happened when Julius Petri was a military physician working in Robert Koch's lab in Germany during the 1880's. Earlier, microbiology labs used to follow the method of pouring agar based nutrient media into an open dish and placing it under a bell jar. The plates were continually exposed to air and the bell jar had to be removed for viewing of the plates. However, the bell jar method resulted in many contaminated cultures, thus frustrating Koch's researchers. Again prior to this, all cultures were grown in glass tubes.
Petri recognized the benefit of growing cultures in open dishes rather than tubes in order to increase the streaking area to obtain isolated colonies. It was 1887 when Fanny Hesse a co-worker in Koch's lab, invented the use of agar to create a solid medium. Julius Petri had the idea of placing a slightly larger glass lid on top of the glass dish that contained the culture media. This method proved to be far simpler and more reliable than the bell jar. Thus the "Petri Plate" was born and is still serving its purpose 121 years later.
Has it been modified?
The dish remains the same today as Petra invented it. Changes are that these days the plate is constructed of disposable polystyrene instead of glass, and features small tabs on the lid to allow limited amount of air exchange, which is necessary for the aerobic growth of bacteria and fungi. The plates are mass produced on large plastic injection molding machines and subsequently sterilised by either gamma radiation or ethylene oxide gas (EtO) before they are dispatched to microbiologists and labs.
Why is it an important invention?
This device is used to culture cells and in simple words this is one device on which cell is cultured in a controlled conditions. This allows researchers to examine the effects of specific conditions and mutations on cell physiology. Cell culture allows the investigation of normal cell physiology and biochemistry of cells. Studies of cell metabolism and the cell cycle. It also allows researchers to examine the effect of various chemical compounds or drugs on a given cell types. For example researchers can examine the toxicity of a certain chemical in a normal cell. Also, the ability of a drug to kill cancer cells can be also tested in cell culture. Most of the chemicals including the medicines are tested in this phase.
Here are some pictures of the chicken grown on the dish....