Introduction and history The concept that cell is the basic unit of life is known as cell theory or cell doctrine. The first attempt to present a theory regarding cellular organization of living beings was made by a French scientist H.I. Dutrochet in 1824. In this context, Dutrochet postulated two views:
The actual cell theory was proposed by M. J. Schleiden, a German botanist. Shleiden found that all plant tissues were made of one or other kind of cells. Therefore, Schleiden (1838) concluded that cells constitute the ultimate units of all plant tissues. In other words, cells are organisms and entire plants and animals are aggregations of these organisms arranged according to a definite law. In 1839, Theodor Schwann a German zoologist studied different types of animal tissues including the development of the embryo. Theodor Schwann concluded that all the organisms are composed of essentially like parts namely cells.
Combined view of Schleiden and Schwann led to the formulation of the cell theory. Cell theory proposed that all living beings whether plants or animals are composed of an assemblage of cells which arise from the pre-existing cells and that the activities of the organism are the outcome of the activities of its constituent cells. Schleiden and Schwann are credited with formulating the observations in the form of a theory. This theory was, however, not able to explain how new cells are formed. Rudolf Virchow (1855) modified the cell theory and stated that new cells develop from the division of pre-existing cells (Omnis cellula-e-cellula). It is known as the law of cell lingeage.
Fundamental features of cell theory The fundamental features of cell theory are as follows:
Objections or shortcomings of the cell theory The shortcomings of cell theory are:
Modern cell theory or cell principle The cell principle is the modified or modern form of the cell theory. The cell theory stands today as cell principle. The main features of cell principle are given below:
Last words The modern cell theory or cell principle is better than cell theory because of the following reasons:
Hakimuddin Kuwakhedawala is based in India with over 15 years experience as a teacher. Teaching and writing are his passion. Most of the articles of Hakimuddin are related to education, exam, environmental problems, etc.
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I think the date of Schleiden is wrongly mentioned here. It should be 1838 but it is written as 1938.
Thank you Deepankar. The error has been rectified.