TERATOLOGY — DEGENERATION. 369 



want of proper nourishment, are capable of producing abortions of 

 various kinds. The non-development of a branch gives rise to clustered 

 or fascicled (fascis, a bundle of twigs) leaves, as in the Larch, and to 

 fascicled twigs, as in a common bird-nest-like monstrosity of the Birch. 

 When the true leaves of a plant are suppressed, their place may be 

 occupied by a tendril, as in Lathyrus Aphaca, in which the stipules 

 perform the functions of leaves (p. 120) ; or the petiole may be 

 developed in a peculiar way, as in the phyllodia (p. 96) of some 

 Acacias. 



Degeneration, or the transformation of parts, often gives rise either 

 to an apparent want of symmetry or to irregularity in form. 

 Branches, when not properly developed, may assume the form of 

 thorns or spines (p. 119), as in the Hawthorn and Wild-plum ; and 

 by culture these spines may be converted into leaf-bearing branches. 

 Leaves often become mere scales, as in Lathrsea, Orobanche, and in 

 Bulbs. The limb of the calyx may appear as a rim, as in some Um- 

 belliferse ; or as pappus, in Compositae and Valeriana. In Scrophu- 

 laria the fifth stamen appears as a scale-like body, called staminodium 

 (fig. 378, p. 227) ; in other Scrophulariacese, as in Pentstemon, 

 it assumes the form of a filament, with hairs at its apex in place 

 of an anther. In -unisexual flowers it is not uncommon to find 

 vestiges of the undeveloped stamens in the form of filiform bodies or 

 scales. To many of these staminal degenerations Linnaeus gave the 

 name of nectaries. In double flowers transformations of the stamens 

 and pistils take place, so that they appear as petals. In Oanna, 

 what are called petals are in reality metamorphosed stamens. In 

 the capitula of Oompositae we sometimes find the florets converted 

 iqto green leaves (fig. 650). Allusion has already been made to the 

 various changes which the dififerent parts of the flower thus undergo. 

 The object of the florist is to produce such monstrosities ; and flowers, 

 which by him are considered perfect, are looked upon by the botanist 

 as imperfect, from the want of the essential organs. 



Cohesion, or the union of parts of the same whorl, and Adhesion, or 

 the growing together of parts of different whorls, are very common 

 causes of changes both as regards form and symmetry. The union of 

 stems gives rise occasionally to anomalies, as in the fasciated stalk 

 of Cockscomb (fig. 251, p. 174), and the flattened stems of some 

 Coniferae (p. 117), and probably also the peculiar stems of certain 

 Sapindaceae and MenispermaccEe of Brazil (p. 62). Some of these,, 

 however, may perhaps be- traced not to union, but to an abnormal 

 development of buds, producing wood only in one direction, in place 

 of aU round. Natural grafts occasionally occur from one branch of a 

 tree uniting to another. Boots also sometimes become grafted, and 

 to this has been attributed the vitality occasionally preserved by the 

 stumps of Spruce-firs which have been felled on the Swiss Alps. The 



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