Dessaignes, who obtained it by oxidizing malic acid (Ann., 1858, 107, p. 251).
The female organs of certain cryptogams, for instance, exert a positive chemiotactic action upon the spermatozoids, and probably, as Pfeffer suggests, the chemical agent which exerts the influence is malic acid.
No other substance, at least, with which he experimented had a like effect, and it is possible that in the archegonium which contains the ovum malic acid is present.
In the last years of his life he returned to the vegetable acids, and investigated citric, malic, oxalic and gallic acids.
Such bases occur almost exclusively in the dicotyledons, generally in combination with malic, citric, tartaric or similar plant-acids.