File:Elementary botany (1905) (14760367676).jpg

Identifier: elementarybotan00atki (find matches)
Title: Elementary botany
Year: 1905 (1900s)
Authors: Atkinson, George Francis, 1854-1918
Subjects: Botany
Publisher: New York : Holt
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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rosette of leaves. The male plants of mnium are easily selected, since the leaves at the endof the stem form a broad rosette with the antheridia, and some sterile threadspacked closely together in the center. The ends of the mass of antheridiacan be seen with the naked eye, as shown in fig. 282. When the antheridia 246 MORPHOLOG Y. are ripe, if we make a section through a cluster, or if we merely tease outsome from the end with a needle in a drop of water on the slide, then preparefor examination with the microscope, we can see the form of the antheridia.They are somewhat clavate or elliptical in outline, as seen in fig. 284. Be-tween them there stand short threads composed of several cells containingchlorophyll grains. These are sterile threads (paraphyses). 518. Sporogonium.—In fig. 280 we see illustrated a sporogonium of mnium,which is of course developed from the fertilized egg cell of the archegonium.There is a nearly cylindrical capsule, bent downward, and supported on a lon^
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Fig. 284. Fig. 283. Antheridium of milium Section through end of stem of female plant of mnium, show- with jointed paraphysising archegonia at the center. One archegonium shows the egg. at the left; spermato-On the sides are sections of the protecting leaves. zoids at the right. slender stalk. Upon the capsule is a peculiar cap,* shaped like a ladle orspatula. This is the remnant of the old archegonium, which, for a time sur-rounded and protected the young embryo of the sporogonium, just as takesplace in the liverworts. In most of the mosses this old remnant of the arche-gonium is borne aloft on the capsule as a cap, while in the liverworts it isthrown to one side as the sporogonium elongates.519. Structure of the moss capsule.—At the free end on the moss capsule * Called the calyptra. MOSSES. 247 as shown in the case of mnium in fig. 280, after the remnant of the arche- gonium falls away, there is seen a conical lid which fits closely over the end. When the capsule is ripe this lid

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