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Show 12 INTRODUCTORY REMARKS. CrrAP. I. the seeds. Sometimes a few would germinate on one side before any on the other, and these were thrown away. But as often as a pair germinated at th same time, they were planted on opposite sides of a pot, with a superficial partition between the two ; an l I thus proceeded until from half-a-dozen to a score or more seedlings of exactly the saine age wer plan ted on the opposite sides of several pots. If one of tho young seedlings became sickly or was in any way injured, it was pulled up and thrown away, as w 11 as its antagonist on the opposite side of the same pot. .As a large number of seeds wore placed on th sand to germinate, many remained after the pair had b on selected, some of which were in a state of gennination and others not so ; and these were own crow 1 c1 together on the opposite sides of one or two rath r larger pots, or sometimes in two long rows out of doors. In these cases there was the most severe strn o-gle for life among the crossed seedlings on on sideb of the pot, and the self-fertilised seedlings on the oth r side, ~nd between the two lots which gr w in competition In the saine pot. .A vast number soon perished, and the tallest of the survivors on both sid s wh n fully grown were measured. Plants treated in this manner, were subjected to nearly the same conditions as those growing in a state of nature, which have to struggle to maturity in the midst of a host of competitors. . On other o.ccasions, from the want of time, the seeds, Instead of be1ng allowed to germinate on damp sand, were sown on the opposite sides of pots, and the fully grown plants measu.red. But this plan is less accurate, as th: seeds somet1mes germinated more quickly on one Sl~e th~n on the other. It was however necessary to aet ln this mannex with some few species, as certain CHAP. I. INTRODUCTORY REMARKS. l3 kinds of seeds would not germinate well when exposed '' to the light; though the glasses containing them were 1 kept on the chimney-piece on one side of a room, and some way from the two windows which faced the N.E.* The soil in the pots in which the seedlings were planted, or the seeds sown, was well mixed, so as to .. be uniform in composition. The plants on the two sides were always watered at the same time and as equally as possible; and even if this had not been done, the water would have spread almost equally to both sides, as the pots were not large. The crossed and self-fertilised plants were separated by a superficial partition, which was always kept directed towards the· chief source of the light, so that the plants on both sides were equally illuminated. I do not believe it possible that two sets of plants could have been subjected to more closely similar conditions, than were my crossed and self-fertilised seedlings, as grown in the above described manner. In comparing the two sets, the eye alone was never trusted. Generally the height of every plant on both sides was carefully measureJ, often more than once, viz., whilst young, sometimes again when older, and finally when fully or abnost fully grown. But in soine cases, which are always specified, owing to the want of time, only one or two of the tallest plants on each side were measured. This plan, which is not a good. one, was never followed (except with the crowded * 'J.1his occurred in the plainest manner wjth the seeds of Papaver vagum anrt Delphinium consolida, and less plainly . with those of Adonis ;:estivalis ami Ononis minutissima. Rarely more than one· or two of the seeds of these four species germinated on the bare sand, though left there fOl' some weeks; but when these same seeds wore placed on earth ih pots, and . covered with a thin layer of sand. they germinated immediately in large numbers. |