[247] For instances of similar changes in _Composites_, see De Candolle, 'Prod.,' t. vi, p. 571, _Centaurea Jacea phyllocephala_. Clos, 'Ann. Sc. Nat.,' ser. iii, tom. xvi, 1851, p. 41. 'Science Gossip,' 1865, p. 104, &c. [248] Kickx, 'Bull. Acad. Belg.,' t. xviii, part 2, p. 288. [249] Weber, 'Verhandl. Nat. Hist. Vereins. f. Preuss.,' &c., 1860, p. 381. [250] Weber, loc. cit. [251] Sauter, 'Flora v. Bot. Zeit.,' 1831, p. 11. [252] 'Descr. et Icon. Plant.' tab. 20. [253] For references see p. 115; see also to Eichler, 'Excurs. Morpholog. de format. flor. Gymnosperm.,' in "Mart. Flor. Brasil," abstracted in English in 'Natural History Review,' April, 1864. [254] "Calyx tunc plane non differt a foliis proxime ipsi praecedentibus." Wolff, 'Theor. Gener.,' Sec. 114. Linn., 'Proleps.,' Sec. 6. Goethe, 'Versuch.,' Secs. 31-38. [255] 'Bull. Soc. Bot. France,' vol. viii, 1861, p. 697. [256] 'Organ. Veget.,' t. i, p. 492, pl. xxxii, f. 6. [257] This distinction between laminar and vaginal venation is well seen in cases like _Mussaenda_, _Calycophyllum_, or _Dipterocarpus_, where the enlarged calycine segment has a strictly vaginal arrangement of its veins, very different from that which occurs in the true leaf-blades. These are cases, therefore, where the sheath of the leaf is unusually enlarged, and are not to be referred, as is often done, to metamorphosis of one or more sepals to perfect leaves. Prolified roses, cherries, &c., furnish frequently parallel cases. With reference to _Mussaenda_, C. Morren held the view that the petal-like sepal was really a bract adherent to the calyx, and incorporating with itself one of the calycine lobes--"soudee au calice et ayant devoree, en englobant dans sa propre masse, un lobe calicinal." The Belgian _savant_ considers this somewhat improbable explanation as supported by a case wherein there were five calyx lobes of uniform size, and a detached feather-veined leaf proceeding from the side of the ovary lower down ('Bull. Acad. Belg.,' xvii, p. 17, _Fuchsia_, p. 169). [258] In this order _Agrostemma Githago_ offers an illustration of a normally leafy calyx. [259] 'Bull. Bot.,' i, p. 6. [260] Wolff's original opinion was that the stamens were equivalent to so many buds placed in the axil of the petals or sepals (see 'Theoria Generationis,' 1759, Sec. 114)--an opinion which more recently has received the support of Agardh and Endlicher. Wolff himself, however, seems to have abandoned his original notion, for in his memoir, "De formatione intestinorum praecipue tum et de amnio spurio aliisque partibus embryonis gallinacei, nondum visis," &c., in 'Comm. Acad. Petrop.,' xii, p. 403, anno 1766, he considers the stamens as essentially leaves. See also Linn. 'Prolepsis,' Sec. viii; Goethe, 'Metam.,' Sec. 46. [261] Mueller (Argov.), in 'Mem. Soc. Phys. et d'Hist. Nat. Genev.,' t. xvii.