In addition to other publications previously mentioned, reference may be made to the following treatises on the subject of ascidia:--Bonnet, 'Rech. Us. Feuilles,' p. 216, tab. xxvi, f. 1, _Brassica_; De Candolle, 'Trans. Hort. Soc.,' t. v, pl. 1, _Brassica_; Id., 'Org. Veget.,' I, 316; 'Bull. Soc. Bot. Fr.,' I, p. 62, _Polygonatum_; 'Bull. Acad. Belg.,' 1851, p. 591, _Rosa_; Hoffmann, 'Tijdschrift v. Natuur. Geschied.,' vol. viii, p. 318, tab. 9, _Ceratonia_; C. Mulder, 'Tijdschrift, &c.,' vol. vi, p. 106, tab. 5, 6, _Trifolium_, _Mimosa_, _Staphylea_;' Molkenboer,' p. 115, t. 4, _Brassica_. FOOTNOTES: [10] See a curious instance of this kind in the branches of _Pinus_. 'Regel. Garten Flora,' vol. 8, tab. 268. [11] 'Bull. Soc. Bot. France,' 1860, p. 881. [12] Ibid., 1861, p. 708. [13] Ibid., 1860, p. 923. [14] 'Proc. Linn. Soc.,' April 5, 1853. [15] 'Organ. Veget.,' pl. iii, fig. 1. [16] 'Bull. Acad. Roy. Bruxelles,' t. xviii, p. i and p. 591. [17] 'Linnaea,' tom. 13, p. 383. [18] 'Verhandl. Nat. Hist. Vereins,' 1859, Bonn, tom. xvi, tab. 3. [19] 'Bull. Soc. Bot. Fr.,' vol. i, p. 62. [20] 'Report of Internat. Bot. Congress,' London, 1866, p. 131, tab. vii, figs. 10-13. [21] 'Bull. Acad. Roy. Belg.,' t. xviii, 2nd part, p. 179. [22] D. C., 'Organ. Veget.,' pl. xvii, fig. 3, and pl. xlviii, fig. 2. [23] 'Mem. Acad. Toulouse,' 1862. [24] Bonnet, 'Recherches Us. feuill.,' pl. xxi, fig. 2. [25] De Candolle, 'Mem. Leg.,' pl. v, fig. 14. [26] 'Phil. Bot.,' Sec. 125. [27] 'Nov. Act. Acad. Nat. Cur.,' 14, p. 642, t. xxxvii. [28] 'Journal of the Linn. Soc. Bot.,' vol. iv, p. 55. [29] 'Bull. Acad. Roy. Bruxelles,' 1838, t. v, p. 582. 'Bull. Acad. Roy. Belg.,' 1852, t. xix, part iii, p. 437. CHAPTER II. ADHESION. Adhesion, so called, occurs either from actual union of originally distinct members of different whorls or from the non-occurrence of that separation which usually takes place between them. It is thus in some degree a graver deviation than cohesion, and is generally a consequence of, or at least is coexistent with, more serious changes; thus if two leaves of the same whorl are coherent the change is not very great, but if two leaves belonging to different whorls, or two leaves in the same spiral cycle are adherent, a deformation in the axis or a certain amount of dislocation must almost necessarily exist. Adhesion as a normal occurrence is usually the result of a lack of separation rather than of union of parts primitively separate. Instances of adhesion between different organs is seen under ordinary circumstances in the bract of the Lime tree, which adheres to the peduncle, also in _Neuropeltis_, while in _Erythrochiton hypophyllanthus_ the cymose peduncles are adherent to the under surface of the leaf.