virchow said all living things are composed of cells, contributing to the cell theory.
who said all living things are composed of cells, contributing to the cell theory?
virchow
cells, which were once invisible to the naked eye, were first seen in 17th century europe with the invention of the compound microscope. robert hooke was the first person to term the building block of all living organisms as "cells" after looking at cork. the cell theory states that all living things are made up of cells. the theory also states that both plants and animals are composed of cells which was confirmed by plant scientist, matthias schleiden and animal scientist, theodor schwann in 1839. 19 years later, rudolf virchow contributed to the cell theory, arguing that all cells come from the division of preexisting cells. in recent years, there have been many studies which question the cell theory. scientists have struggled to decide whether viruses are alive or not. viruses lack common characteristics of a living cell, such as membranes, cell organelles, and the ability to reproduce by themselves. viruses range from 0.005 to 0.03 micrometers in size whereas bacteria range from 1-5 micrometers. modern day cell biology research looks at different ways to culture and manipulate cells outside of a living body to further research in human anatomy and physiology, to derive treatments and other medications, etc. the techniques by which cells are studied have evolved. advancement in microscopic techniques and technology such as fluorescence microscopy, phase-contrast microscopy, dark field microscopy, confocal microscopy, cytometry, transmission electron microscopy, etc. have allowed scientists to get a better idea of the structure of cells.
cell biology
in it schwann declared that "all living things are composed of cells and cell products". 





























he drew three further conclusions about cells, which formed his cell theory or cell doctrine. the first two were correct:





























bullet::::1. the cell is the unit of structure, physiology, and organization in living things.





























bullet::::2. the cell retains a dual existence as a distinct entity and a building block in the construction of organisms.





























by the 1860s, these tenets were the accepted basis of cell theory, used to describe the elementary anatomical composition of plants and animals.
theodor schwann