Julius Richard Petri

Julius Richard Petri (Barmen, May 31, 1852 – Zeitz, Germany, December 20, 1921) was a german microbiologist who is credited with inventing the Petri dish whilst working as an assistant to Robert Koch¹.

After primary and secondary education, he studied medicine at the Kaiser Wilhelm-Akademie for military physicians  between    1871 and 1875. He completed his doctorate as a physician at the Charité in Berlin, which he obtained in  1876. Between 1876 and 1882 he served as a military doctor and was an assistant to Robert Koch (Nobel Prize in Physiology    and  Medicine in 1905), and it was whilst working with the famous German scientist when he invented his famous petri  dish in  1877.  Basically it joined two round clear glass covers that allowed samples to isolate different organisms and  allowed them to  grow in  controlled conditions. Petri designed a container about ten centimeters in diameter with edges of  1 to 1.5 cm high.  This allowed the  molten to extend over a large area of ​​0.5 to 0.7 cm thick agar.

What seemed simple  and currently more than normal, at the time but it was a revolution for microbiology and medicine.Placa_petri
For the nineteenth century highly contagious epidemics were  declining population of half the world. Thanks to the petri dishes, they  were able to isolate microorganisms that caused diseases such as diphtheria or cholera, then finding the cure thereof. Until that time the cultures were made by melting the solid agar media and then extending on one side of a test tube. This made it difficult to obtain separate colonies and studied so few extensions.
The petri dish, widely used in microbiology studies to culture microorganisms