=Enlargement of the fruit.=--Most cultivated fruits are in a state of true hypertrophy. Girod de Chantrans, after many trials, succeeded in producing a peculiar variety of pea with pods double the ordinary size.[506] M. Clos[507] mentions a case wherein the carpels of _Delphinium dictyocarpum_ were hypertrophied. The change in size may or may not be attended by a difference in form; thus, in certain _Leguminosae_, as _Medicago lupulina_, _Melilotus leucantha_, the carpels are sometimes hypertrophied and elongated, so as to resemble a claw or hook.[508] The fruit of the common groundsel (_Senecio vulgaris_) is in its normal condition two or three times shorter than the involucre, and cylindrical for its whole length, but it frequently happens that the fruits become as long as the involucre itself, and taper from the base upwards, so as to become beaked. Under this head may also be mentioned the fleshy bulbils that are found in the capsules of _Crinum_, _Amaryllis_, and _Agave_. These are true seeds enormously dilated.[509] In these seeds the outer coating becomes very thick and fleshy, and is traversed by spiral vessels. It is obvious that very important results in a practical point of view may be and have been arrived at by cultivators availing themselves of this tendency of plants to increase in dimensions under certain circumstances. It is needless to do more than refer to the many fruits, vegetables, and cereals, which have thus become enlarged and improved by careful selection and rearing. =Alterations of consistence= often accompany changes in size. The change may be one whereby the tissues become unusually hardened, by the excessive formation of secondary woody deposits, or softer and more succulent than ordinary, from the formation of an inordinate amount of loose cellular tissue. Generally speaking, the appearances presented in such cases are not sufficiently striking to demand notice other than as regards their size. One illustration, however, may be cited from its singularity. This was the case of a dahlia, in which the centre of the flower was occupied by a projecting knob as large as a walnut, brown in colour, and very hard in texture. This knob was nothing but the enlarged and indurated extremity of the common receptacle, destitute of the scales and florets which usually spring from it. No insect-puncture could be detected, and no other reason for this peculiarity could be ascertained. FOOTNOTES: [488] On the subject of knaurs, the reader is referred to Trecul, 'Ann. Sc. Nat.,' 3 ser., vol. xx, p. 65; Lindley, 'Theory of Horticulture;' Rev. M. J. Berkeley, 'Gardeners' Chronicle,' 1855, p. 756. [489] Jaeger, 'Flora.' 1860. p. 49, tab. i. [490] 'Revue Horticole,' 1868, p. 110, figs. 12, 13.