Sol-gel theory of protoplasm was proposed by Hyman. Protoplasm is the highly organized and most active chemical system of nature with maximum energy conversion. These two states are reversible. This Sol ⇋ gel conversion is due to colloidal nature of protoplasm cytoplasm is differentiated into outer gel like ectoplast (plasmagel) and inner sol part called endoplast (plasmasol). Pandn and Mast gave Sol-gel theory of Amoeba locomotion later.