. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. 400 THE NON-VASCULAR PLANTS. cilia. They are so small that a film of dew is quite enough for them to swim in, and when the sperms of Marchantia are discharged from the antheridia, there is nearly always enough moisture on the surface of the plant to permit them to swim to the archegonia. To reach the eggs they have to swim up, but at the time when swimming occurs the stalks of the archegoniophores are quite short; not nearly so long as they become later. M
. Plant life and plant uses; an elementary textbook, a foundation for the study of agriculture, domestic science or college botany. Botany. 400 THE NON-VASCULAR PLANTS. cilia. They are so small that a film of dew is quite enough for them to swim in, and when the sperms of Marchantia are discharged from the antheridia, there is nearly always enough moisture on the surface of the plant to permit them to swim to the archegonia. To reach the eggs they have to swim up, but at the time when swimming occurs the stalks of the archegoniophores are quite short; not nearly so long as they become later. Most of the liverworts do not bear their archegonia upon stalked organs, and of course in such cases the journey of the sperms to the eggs is much simpler than in Marchantia. What happens after fertihzation is particularly important for you to note. You remember that in (Edo- gonium the fertilized egg or oospore does not grow directly into a plant like its parent; it divides into four spores, and each of these is capable of producing a new plant. In liverworts we find this process carried still further. We find "the oospore not only forming a number of spores; we find it growing into a special organ many of whose cells are not spores at all. This organ is called a sporogonium. (See Figure 198.) The sporogonium in Marchantia is an organ big enough to be seen easily by the naked eye. It contains spores, but it also contains many cells of other kinds. Be- sides the cells of the wall and the foot and the seta, there are the elaters, peculiar spirally-marked cells which appear among the spores and, by twisting as they dry, push the Fig. IQ7'. "^ A young an- theridium of Marchantia. Also two of the biciliate sperms from a ripe an- Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Coulter, John G
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1913
