Creating a microscope with a small increase (35-40 times). Studying a section of elderberry cork under a microscope by R. Hooke, and determining a structure similar to a honeycomb, which he later called cells. Levenguk improved the microscope by polishing the lenses (glasses) of the previous microscope, which increased the resolution by 200 times. This allowed us to make out the simplest animals and bacteria in a drop of water. In 1831, R. Brown discovered the nucleus in animal cells. T. Schwann and M. Schleiden created a cellular theory, with the main idea that all living organisms consist of their cells. In the middle of the 19th century Cell division was discovered.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.