These are called, in Low German, "gäscht" and "gischt"; in Anglo- Saxon, "gest," "gist," and "yst," whence our "yeast."

Thus "hefe" is derived from "heben," to raise; "barm" from "beren" or "bären," to bear up; "yeast," "yst," and "gist," have all to do with seething and foam, with "yeasty" waves, and "gusty" breezes.

For est and eth, we find sometimes the consonants only; sometimes, ist or yst, ith or yth; sometimes, for the latter, oth or ath; and sometimes the ending was omitted altogether.