In a recent work, entitled “Wahre Parthenogenesis bei Schmetterlingen und Bienen”—Real Parthenogenesis in Butterflies and Bees, Von Siebold, after reviewing the present condition of the subject, distinguishes the so-called alternate generation from parthenogenesis, and limits Professor Owen's term to reproduction by unimpregnated females.

He has ascertained that this real parthenogenetic mode of reproduction occurs in certain moths—Solenobia lichenella and triquetrella, the larvæ of which are sac-bearers; and in Psyche helix, the larva of which constructs one of those remarkable spiral sacs which have been mistaken for the shells of molluscs.