it is suggested that divalent cations make spores resistant to drying and pressure by cross-linking negatively charged groups within the protoplast , and that together with hydrogen ions they neutralize the negatively charged groups , thus preventing the swelling of the protoplast , loss of refractility and fall in extinction which occur when divalent cations are replaced by monovalent cations .
C0033727
hydrogen ions
C0007449
monovalent cations