If a future biology scientist looks back at the improvements and achievements that mankind has accomplished so far, it’s
of no doubt that he will definitely give very special importance to the twentieth century as it has given the opportunity to
understand the most of the life’s processes and diseases. At the end of the 19th century most of the fundamental ideas about life and its progression was conceived by different philosophers in different ways, which resulted in the formation of isolated departments of biology like Darwin helped to understand the evolutionary aspects of the organisms; Mendel discovered some of the basic rules of the inheritance; many embryologists like de Vries have given idea about how the life starts form the single cell.
These extraordinary ideas were not been able be linked together to understand better about the process or life and that was made possible during the twentieth century. As the identification of the genes, which are localized in the
chromosomes - at the beginning the unit of Mendelian hereditary, the stimulating force of Darwinian evolution, and the regulatory switch for the development - were made in the twentieth century it was possible to unite these different fields and arrive at a position which enable us to understand the process of life. The person called the Thomas Hunt Morgan belonging to Columbia University did this remarkable invention.
Morgan has given a clear idea about the gene, which has the information about the chemical nature of the gene that comprise the structure and function, the method by which the genes multiply themselves, the result of the gene mutation, the basis of the genetic diseases, etc. Morgan has found the works of the teacher and monk of Augustinian monastery - Mendal who's work has certain similarity with his present investigation and rediscovered his works published in ‘Proceedings of the Natural Science Society of Brno’ in 1866. The animal he selected was the ‘Drosophila,’ which had very short lifecycle and only limited number of chromosomes that made the study more easy and comfortable. In 1910, Morgan was able to succeed in the study and formed the basis of the modern ‘Genetics.’ In subsequent studies he has also found that the characters that appear in organisms is not only because of the inheritance, but also related to sex. This finding formed the core to the idea of ‘chromosomal theory of hereditary.’