AUTHOR'S NOTE Chemical science has enjoyed a world of challenge in appraising the nature and inter-relationships of the elements, but for an emergent biological science it is especially important to consider the relationships of the elements and their compounds to an aqueous solvent. Hydrational potentiality is the ionic attribute which organic nature, from its earliest amoeboid beginnings to its present production of astounding types of intellectuals, has used extensively in its embodiment of the precious fire called life. To biology as the life science hydration thus is a matter of most intimate and timely concerns.