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

BOOK 4

manufacturing chimeras at command. The stem of one kind of plant (tomatoes and other species of Solanum have chiefly been

Fig. 164.

used, but it has succeeded with other plants such as poplars) is cut across obliquely, and the top of the stem of another species grafted on. After the two have united, the stem is cut straight across the joint ; from

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THE SCIENCE OF LIFE

The Continuity of the Generations.

The little jellyfish Syncoryne has its mouth on the end of a long proboscis, from which it buds off new jelly-fish which are eventually liberated to grow up and repeat the process.

CHAPTER 2

the cut surface new stems and buds are formed and a certain proportion of these give skin-

and-core chimeras, or graft-hybrids, as they are generally called.

In Fig. 163 are seen some of these vegetable freaks. Sometimes the skin is only one cell-layer thick, sometimes two ; and the grafthybrid will differ in appearance accordingly. The growthrates of the two components may be different; and in such a case the graft-hybrid will either have astretched, tense look, or its leaves will be all folded and rucked up because their skin is growing too fast for their central parts.

§ 9 What ts Meant by the Germ-plasm

It is evident from what has gone before that, whether reproduction is sexual or whether it is not, there is material continuity between one generation and the next. The individual is a detached bit of its parent.

Weismann, the great German zoologist, pointed out in the latter half of the last century that that part of a man which grew