1. Hooke Leeuwhenhoek's microscopes allowed observation of celluary structure- > living things are made of cells.
2. Microscope allowed observation of cell's carrying out life processes, showing they were the smallest unit of life.
3. Remak was able to observe a single cell during cell division dividing to form two indicical cells, showing that new cells come from pre-exisiting cells.
4. Microscopes allowed observation of organelles, which showed they did not carry out all the life processes, which meant cells were the smallest unit of life.