. Textbook of botany. Botany. THE BRACKEN FERX 105. Fig. 57. — A fern anthero- zoid. From a preparation by Dr. W. X. SteU. gametes are borne dose together on the same plant, it is probable that as a rule self-fertilization — the union of an egg with an antherozoid produced by the same plant—does not occur in the fern. That it does not is suggested by the fact that the antherids usually lipen and discharge their antherozoids before the archegones on the same plant are mature. This would seem to make cross-fertilization necessary — that is, the union of an egg and an antherozoid borne by differe
. Textbook of botany. Botany. THE BRACKEN FERX 105. Fig. 57. — A fern anthero- zoid. From a preparation by Dr. W. X. SteU. gametes are borne dose together on the same plant, it is probable that as a rule self-fertilization — the union of an egg with an antherozoid produced by the same plant—does not occur in the fern. That it does not is suggested by the fact that the antherids usually lipen and discharge their antherozoids before the archegones on the same plant are mature. This would seem to make cross-fertilization necessary — that is, the union of an egg and an antherozoid borne by different plants. On the other hand, young antherids are sometimes found on the same plants with weU- developed archegones, and it is quite possible that self-fertilization occurs now and then. Cross-fertilization is made easier by the fact that sexual plants conmionly grow in groups, be- cause many spores were dropped and germinated near one another. Since these Uttle plants grow in moist places, there is enough water present much of the time on their lower surfaces so that the antherids can open and the antherozoids can swim to the mouths of the archegones either on the same or on neighboring plants. 132. Development of the Asexxial Plant. — Doubtless it often happens that more than one egg is fertihzed and so that more than one zygote is formed in the archegones of a single plant; but we seldom find that more than one zygote has developed into a plant of the next generation. This is prob- ably because the new plant growing from the zygote receives food for some time from the sexual plant that bore the egg; since the sexual plant is small and can supply only a limited amount of food, only that one embryo develops which has an advantage because of its greater vigor or its better location; the less fortunate enibr\'os are star\'ed and cease to grow. The zygote, like the zygote of the moss, germinates in the arche- gone. \' early the (the young asexual plant. Fig
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