What was anton van leeuwenhoek's contribution in the development of cell theory?

He developed and improved the microscope. He was also the first to discover single-cell organisms that he called animalcules.

He invented the first practical microscopes which was used to see bacterial cell.

Explanation:

Microscopic study was done by Anton van Leeuwenhoek who was a draper and he had a great interest in microscope. This helped in mixing the lens and making a microscope which was used to see cell.

This microscope had a magnification of 270 x, which was of great help when visualizing such a small organism that was not seen by naked eyes.

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex