LIFE SUBSTANCE: THE PROTOPLASM

What  is life ? What is to be alive? These are the questions which have not  been satisfactorily  answered even to this date .Many attempts  have already been made  and are being made  to disclose the mystery of life but we   have still not succeeded  .We know  only this  that  the life is the quality of the living substance,that is , the protoplasm , and it is always associated  with the protoplasm . Thus  protoplasm  is the physical basis of the life.                                                                                                                                                                             Discovery of Protoplasm                                                                                                                                                  The  protoplasm in the cell  was observed by corti  as  early as 1772 .In 1835 ,Dujardin  noted the constant  occurence  of a jelly -like  substance ,unlike ordinary  gelatin  or albumin in  cells of certain   simple animals ,for which he proposed  the name  sarcode .He  recognised  it as  the living material  of these animals  .Four years later ,Purkinje [1839] coined  the name  protoplasm  for the sarcode .In 1846 Von Mohl  also  proposed the name  protoplasm  for a substance which he found  in the cell  of plants in 1861 Max Schultze observed  the cell  contents of protzoa  and of plants and animal cells .He concluded  that the  contents of all cells were essentially    similar, and  he proposed  a theory which was later named  protoplasm  theory  by  Hertwig [1892] .This  theory postulates that the cells are accumulation of the protoplasm  with the  nucleus and a cell membrane .This theory  established the close  similarity of the living  substance of animals and plants  .Huxley [1968] defined protoplasm  as the physical basis  of life.                                                                              STRUCTURE OF PROTOPLASM                                                                           The protoplasm  is a complex mixture of  many chemical substances  .It keeps living thing  alive .Rather , it houses the life .Therefore , it is known as  life substance .The body  of all living  organisms  is composed  of the protoplasm  .The body  and cells  of different  organisms  differ  greatly  from one another  but there  is a basic  similarity in physical and chemical  structures  of their protoplasm  .The living state  of the protoplasm  is due to  its  composition   and physico-chemical  properties.