=Formation of ascidia or pitchers.=--In the preceding paragraphs, the formation of tubular or horn-like structures, from the union of the margins of one organ, or from the coalescence, or it may be from the want of separation of various organs, has been alluded to, so that it seems only necessary now, by way of summary, to mention the classification of ascidia proposed by Professor Charles Morren[29], who divides the structures in question into two heads, according as they are formed from one or more leaves. The following list is arranged according to the views of the Belgian savant, and comprises a few additional illustrations. Those to which the ! is affixed have been seen by the writer himself; the * indicates the more frequent occurrence of the phenomenon in some than in other plants. Those plants, such as _Nepenthes_, &c., which occur normally and constantly, are not here included. Possibly some of the cases would be more properly classed under dilatation or excavation. ASCIDIA. A. _Monophyllous_. 1. Sarracenia-like pitchers, formed by a single leaf, the edges of which are united for the greater portion of their length, but are disunited near the top, so as to leave an oblique aperture. *Brassica oleracea (several of the cultivated varieties)! *Tilia europaea! Pelargonium inquinans! Staphylea pinnata. Amorpha fruticosa. Pisum sativum! Lathyrus tuberosus. Vicia sp. Gleditschia sp. Ceratonia siliqua. Trifolium repens! Cassia marylandica. Mimosa Lophantha. Rosa centifolia. gallica. Begonia sp. Bellis perennis! Nicotiana sp. Goodenia ovata! Antirrhinum majus! Vinca rosea. Polygonum orientale. Aristolochia sipho? Codiaeum variegatum var.! Spinacia oleracea. Corylus avellana! Polygonatum multiflorum. Xanthosoma appendiculatum! 2. Calyptriform or hood-like pitchers, formed by the complete union of the margins, and falling off by a transverse fissure (as in the calyx of Escholtzia). Tulipa Gesneriana. B. _Polyphyllous._ 1. Diphyllous, formed by the union of two leaves into a single cup, tube, or funnel, &c. Pisum sativum (stipules)! Crassula arborescens. Polygonatum multiflorum. 2. Triphyllous, formed by the union of three leaves. Paris quadrifolia var. Besides the above varieties of ascidia formed from the union of one or more leaves, there are others which seem to be the result of a peculiar excrescence or hypertrophy of the leaf. Such are some of the curious pitcher-like structures met with occasionally in the leaves of cabbages, lettuces, Aristolochia, &c. See Hypertrophy, cup-like deformities, &c.