The Collaborative International Dictionary of English v.0.48:

Protoplast \Pro"to*plast\, n. [L. protoplastus the first man,
   Gr. ? formed or created first; ? first + ? formed, fr. ? to
   form.]
   [1913 Webster]
   1. The thing first formed; that of which there are subsequent
      copies or reproductions; the original.
      [1913 Webster]

   2. (Biol.) A first-formed organized body; the first
      individual, or pair of individuals, of a species.
      [1913 Webster]

            A species is a class of individuals, each of which
            is hypothetically considered to be the descendant of
            the same protoplast, or of the same pair of
            protoplasts.                          --Latham.
      [1913 Webster]
      [1913 Webster]

WordNet (r) 3.0 (2006):

protoplast
    n 1: a biological unit consisting of a nucleus and the body of
         cytoplasm with which it interacts [syn: energid,
         protoplast]