Ernest Everett Just was an African American biologist who made significant contributions to the field of cell biology and the development of the cell theory. His work paved the way for further research and understanding of one of the fundamental units of life.

The Cell Theory

The cell theory is a fundamental concept in biology that explains that all living organisms are composed of cells. It also states that cells are the basic unit of life and that all cells arise from pre-existing cells. The cell theory was first proposed by Matthias Schleiden and Theodor Schwann in the mid-19th century, but it was later refined by many other scientists, including Ernest Everett Just.

Ernest Everett Just’s Contributions

Ernest Everett Just’s work on cell biology focused mainly on the fertilization process in marine organisms. He studied sea urchins, which allowed him to observe how sperm cells interact with egg cells during fertilization.

Through his research, he discovered that there is a specific area on the surface of an egg cell called the “vital spot.” This spot is where sperm cells attach to initiate fertilization.

Just also discovered that during fertilization, there is a chemical reaction between the egg and sperm cells that triggers a series of changes in the egg’s membrane. These changes prevent other sperm from entering and fertilizing the same egg.

Furthermore, Just’s research showed that each cell has a specific role to play in an organism’s development. He observed how certain cells become specialized over time to perform specific functions within an organism.


In conclusion, Ernest Everett Just made significant contributions to our understanding of cell biology and helped refine our knowledge of the cell theory. His work on marine organisms provided insights into how fertilization occurs and gave us a better understanding of how each cell plays a critical role in an organism’s development. We owe much to his groundbreaking research and his dedication to the field of biology.