100 ANOMALIES AND TRANSFORMATIONS OF LEAF-BUDS. 



is detached in the course of growth, and forms an independent plant. 

 The new bulbs feed on the parent one, and ultimately cause its 

 absorption. The scales are sometimes all fleshy, as in the scaly or naked 

 bulb of the white lily (fig. 209 e e e), or the outer ones are thin and 

 membranous, overlapping the internal fleshy ones, and forming a 

 tunicated bulb, as in the Onion, Squill, and Leek (fig. 207). 



195. The form (x,oofin s a stump) has already been noticed under 

 the head of subterranean stems (^[ 70, fig. 93). It may be considered 

 as a bulb in which the central portion or axis is much enlarged, 

 while the scales are reduced to thin membranes. Some have called it u 

 solid bulb. It is seen in the Tulip, Colchicum, Crocus, and Gladiolus. 

 It produces either terminal buds, as in Gladiolus and Crocus, in which 

 several annual additions to the corm remain attached together, and 

 the newly produced corms come gradually nearer and nearer to the 

 surface of the soil ; or lateral buds, as in Colchicum, represented at fig. 

 03, where r indicates the roots, / the leaf, a 1 the stem or axis of the 

 preceding year withered, a" the secondary axis, or the stem developed 

 during the year, and taking the place of the old one, and which, in 

 its turn, will give origin to a new axis, a'", on the opposite side, 

 according to the law of alternation. The new axes or corms being 

 thus produced alternately at either side, there is very little change in 

 the actual position of the plant from year to year. Bulbs and corms 

 contain a store of starch and of other substances, for the nourishment 

 of the young plants. 



196. Anomalies and Tranaformations of I-caf-buds. Leaf-buds arise 



from the medullary system of the plant, and in some instances thev 

 are found among the cellular tissue, without being in the axil of leaves. 

 In this case they are extra-axillary, and have been called adventitious 

 or abnormal. Such buds are produced after the stem and leaves have 

 been formed, and in particular circumstances they are developed like 

 normal buds. What have been called embryo-buds, are woody nodules 

 seen in the bark of the Beech, Elm, and other trees. They are looked 

 upon as partially developed abnormal buds, in which the woody matter 

 is pressed upon by the surrounding tissue, and thus acquires a very 

 hard and firm texture. When a section is made, 

 they present woody circles arranged around a 

 central pith, and traversed by medullary rays 

 (fig. 210). The nodules sometimes form knots 

 on the surface of the stem, at other times they 

 appear as large excrescences, and in some cases 

 twigs and leaves are produced by them. Some 

 consider embryo-buds as formed by layers of 

 woody matter, which originate in the sap con- 



Fig. 210. Vertical section of a nodule, , or embryo-bud embedded in the bark of the Cedar 

 forms a projection on the surface. The woody layers form zones round a kind of pith. 



