The science of life : fully illustrated in tone and line and including many diagrams

HOW INDIVIDUALS ORIGINATE

way incommoded by their unnatural compositeness ; and by similar methods a salamander leg, half albino and half normal, can be built up. But the climax is reached in plants ; for in them not only can such side-byside patchworks exist, but, even among the highest groups, composite organisms can be produced, made up of a skin of one kind of plant enclosing a core belonging to another kind. Sometimes these strange chimeras arise spontaneously from the junctional tissue where a graft has been made. The ornamental shrub Cytisus adami, often cultivated in gardens, apparently arose in this way, and consists of a skin, one cell-layer thick, of the purple broom, Cytisus purpureus, Over a core of the ordinary yellow laburnum, Cytisus laburnum. Occasionally one of the parts gets the upper hand: the core bursts through, makes a bud and a strong-built,

ye llow-flowerin g Above, slices, seen under the microscope, through p the Purple Broom (Cyttsus pu adami (centre). The surface ce

branch of pure

core out of its room one layer thick over a core of laburnum. A sprig of each The laburnum sprays have large yellow flowers and are pendent ; 1 i and up and have smaller purple flowers. The graft-hybrid has pendent sprays with medium-size

proper share in bud, and there grows a branch of quite different character, bushy and purpleblossomed—pure furpureus. Such hand-inglove unions are possible even between tissues of different genera of plants. Old stocks of hawthorn (Crategus), grafted with

Fig. 163. A Plant Chimera.

etals of the common Yellow Laburaum (i), rpureus), right, and the graft-hybrid between them, Cptisus hs of We purple broom are coloured purplish (shaded). Those laburnum results ; of the laburnum are yellow (dotted), with occasional patches of brown cells (heavily dotted) or skin shoulders which give rise to the dark streaks on the petal. Cytisus adami consists of a skin of purple

kind of plant is drawn below. those of purple broom stand

light purplish flowers.

medlar (Mespilus), have sometimes given rise. to branches consisting of a core of hawthorn with a tissue-glove of medlar fitting over it.

Recently a way has been found for

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