The first microscope was built by Zacharias janssen, which was first modified by Galileo. Then Robert Hooke developed a new microscope with which he studied the internal structure of a number of plants. His work is famous for the study of cork cells.
In 1665, Robert Hooke wrote a book “Micrographia”. He took a piece of cork and prepared thin slice of it which was observed under the microscope. The slice of cork was found to have a honey comb structure with a number of box like compartments which were named as cells (Latin cella – hollow spaces or compartments). Robert Hooke regarded these structures as passages for conducting fluids. The “cells” of Hooke actually were the cell walls enclosing spaces left by dead protoplasts.
The term “cell” is actually a misnomer as a living cell is neither hollow nor always covered by a wall. Prior to Hooke, cells were observed by Malpighi, who called them saccules and utricles. Leeuwenhoek observed bacteria, protozoa, spermatozoa, red blood cells, etc. Lamarck remarked that ‘no body can have life, if its constituent parts are not formed by cells.’ Dutrochet had stated ‘all organic tissues are really globular cells of an extreme smallness which are united by cohesion’. Robert Brown discovered the presence of nucleus in the cells of orchid root. Dujardin discovered the living semifluid substance of cells which was named sarcode. Alfonso corti observed living substances in the cells. Schleden found that all plant cells have similar structure, i.e., cell wall, a clear jery-like substance and a nucleus. Schwann discovered that animal cells lacked cell wall. Purkinje renamed sarcode or the jelly like substance of the cells as protoplasm. Cell membrane was discovered by Schwann but was provided with a name by Nageli and Cramer.
