Unpublished paper and letter, 'De causa ascensus et descensus succi nutritii in vegetantibus' ['Cause of the ascension and descension of the juices that nourish plants'] by Jules de Vian De Vian writes on the 'juice' that nourishes plants, deducing that moderate heat is the main factor behind circulation of this juice within the plant. Preceded by a covering letter from de Vian to an unknown recipient. Subject: Biology / Botany [1793]