Reticular theory:
This theory was postulated by Klein, Comoy, etc. It suggests that protoplasm consists of a reticulum of fibres in its hyaloplasm.
The organic material which consists of proteins and carbohydrates in suspension may be either hydrophilic (water-loving) or hydrophobic (water-hating). The hydrophilic particles occur surrounding the water molecules. The attraction between protein and water is due to electric charges that hold them together.
The physical properties of protoplasm are principally due to the various chemical inclusions in a gel phase. A gel is a group of suspended particles in a semi-solid condition or jelly-like state. The molecules of a gel are held together by various types of chemical bonds of varying strength.
The stability of bond depends upon the type of bond and strength of bond. The gel may become more liquid than solid. This process is called solation and the liquid state as sol. Thus, the colloidal protoplasm which is in gel form can change into sol form by solation and the sol can change into gel by gelation. These gel-sol conditions of colloidal system are prime basis for mechanical behaviour of cytoplasm.
Protoplasm is neither a good nor a bad conductor of electricity. It forms a delimiting membrane on coming in contact with water and solidifies when heated.