Robert Hooke was a 17th-century genius who, apart from his contribution to mathematics, mechanics and astronomy, is highly regarded for his contribution to cell theory and the invention of the microscope. He was also well known for discovering the law governing the stretch of elastic materials, discovering celestial objects and upgrading devices for weather measurement.

Robert Hooke was born in 1635 on an island named Isle of Wight on the southern coast of England. During most of his childhood, he could not attend school due to deteriorating physical health with severe cases of smallpox. Yet he showed a commendable mechanical ability by building a toy boat along with cannons that could fire and building a wooden clock. As a teenager, he started studying at Westminster College, where he discovered his unique talents in mathematics, languages and mechanics. When he enrolled in Christ Church College of the University of Oxford, he grew a passion for building telescopes. 

Prior to 1665, humans were unaware of the fact that microscopes and microscopic worlds existed. Although due to the expanded use of lenses for eyeglasses, simple microscopes were used in the 13th century. Around 1620 compound microscopes were introduced in Europe, which combined an objective lens and an eyepiece to view an image with higher magnification. 

In 1665, interested in learning about the microscopic world, scientist Hooke improved the design of Anton van Leeuwenhoek’s simple microscope or magnifying glass, which had limited magnification and created a compound microscope with 300x magnification. Hooke embraced one of the first microscopes, improved them and utilised them in further discovery of nature. He designed and developed a light microscope, where three glass lenses and a stage light were used to illuminate and magnify objects to be examined. Hooke’s microscope was about six inches long and designed with two convex lenses inside and examined objects under reflected light for observations. With the help of his microscope, Hooke examined and discovered a diversified collection of organisms. Hooke also used a simpler microscope which had a single lens to examine specimens more clearly with directly transmitted light. 

Robert Hooke’s microscope invention was published in his book Micrographia to reveal the existence of a previously unknown world. Micrographia was an illustrated collection of his findings using the Microscope he had developed. 

The discovery of cells was made possible because of the advancements in the microscope. Therefore Robert Hooke’s contribution to Cell theory is vital. In his book Micrographia, Hooke provided detailed 60 observations of various specimens under a compound microscope. One observation included very thin slices of a bottle cork. He discovered numerous tiny pores, which he described as “cells”. The word was a Latin derivation of the word Cella meaning a small room where monks lived, and the word Cellulae meaning the six-sided or hexagonal cell of the honeycomb. He illustrated these findings in his book Micrographia.

However, scientist Hooke was unable to understand the real structure or function of those “cells”. He thought the empty cell walls of plant tissues to be cells. Due to limited magnification, he could not understand that he was observing other internal components. He considered the cellulae to be dead, and therefore it did not indicate the existence of the nucleus and other organelles of living cells. Hooke also observed a bluish-coloured mould found on leather. He couldn’t observe the seeds, which could indicate the theory of the mould being multiplied in quantity. He suggested that it was due to natural or artificial heat leading to spontaneous generation.

Still, we can not ignore the fact that Hooke’s discovery built the foundation of understanding cell theory, where a cell is the smallest unit of life. In the early 1800s, scientists had already observed cells of different organisms. This led two German scientists, namely Theodor Schwann and Matthias Jakob Schleiden, to propose cells are the basic blocks of all living things. When in 1850, a German Doctor, Rudolf Virchow, studied that cells were dividing and forming new cells, he realised that living cells arise from other living cells through division. These ideas by Schwann, Schleiden and Virchow led to the formation of cell theory, which is the fundamental theory of the study of biology. The theory states:

However, based on Robert Hooke’s invention, there has been several modern version and opposing concepts of cell theory. Besides playing a pivotal role in developing cell theory, Hooke also mentioned the idea of combustion developed by Boyle and Hooke in the book Micrographia. He concluded that combustion involves a substance that is in the air, and respiration is also dependent upon a component in the air. This could have led to the further discovery of oxygen. Modern Science will always be grateful to the contribution of Robert Hooke.