This document discusses protoplast isolation and fusion. It defines a protoplast as a plant, bacterial, or fungal cell that has had its cell wall removed, leaving the plasma membrane intact. The document outlines the history of protoplast isolation, from the first isolation in 1892 to the use of commercial enzyme mixtures in the 1960s. It also describes how protoplasts can be fused using polyethylene glycol or other fusogens to create somatic hybrids for plant breeding purposes.