The Collaborative International Dictionary of English v.0.48:

Plasmon butter \Plasmon butter\, and resembles clotted cream in
   appearance.
   [Webster 1913 Suppl.] Plasson \Plas"son\, n. [NL., fr. Gr. ?
   to form.] (Biol.)
   The albuminous material composing the body of a cytode.
   [1913 Webster]

   Note: It is considered simpler than protoplasm of an ordinary
         cell in that it has not undergone differentiation into
         the inner cell nucleus and the outer cell substance.
         --Haeckel.
         [1913 Webster]