Schleiden and Schwann both together discussed Schwann’s hypothesis and they formulated cell theory. The important aspects of cell theory are:
All living organisms are made up of minute units, the cells which are the smallest entities that can be called living.
Each cell is made up of protoplasm with a nucleus and bounded by plasma membrane with or without a cell wall.
All cells are basically alike in their structure and metabolic activities.
Function of an organism is the sum total of activities and interaction of its constituent cells.