. A compendium of general botany. Plants. Fig. 159. (After Berthold and Landois ) body of the ovule (Jj) with the embryo-sac {c) and one or two integuments; the latter {d, f) form the micropylar opening {e). The hilum is the point where the funiculus {a) is attached to the placenta; the chalaza (A) is the zone at the base of the ovule from which the tegumentary layers take their origin; the rajyhe (seam) is the line of union between the funiculus and ovule in anatropous ovules. In semiauatropous (amphitropous) ovules the micropyle and chalaza are about equidistant from the hilum (see Fig. 159,
. A compendium of general botany. Plants. Fig. 159. (After Berthold and Landois ) body of the ovule (Jj) with the embryo-sac {c) and one or two integuments; the latter {d, f) form the micropylar opening {e). The hilum is the point where the funiculus {a) is attached to the placenta; the chalaza (A) is the zone at the base of the ovule from which the tegumentary layers take their origin; the rajyhe (seam) is the line of union between the funiculus and ovule in anatropous ovules. In semiauatropous (amphitropous) ovules the micropyle and chalaza are about equidistant from the hilum (see Fig. 159, 3). The anatropic and campylotropic ovules may further be apotropous^ epitropous., or pleurotrop)ous, according to whether the ovule is turned toward the base (apotropous), the apex (epitropous), or the side (pleurotropous) of the ovary. Such variations in position are intimately associated with the function of the pollen-tube. The Eiiihryo-sac.—Immediately before fertilization the embryo- sac of angiosperms (monocotyledons and dicotyledons) contains, as a rule, three cells near the micropyle and frequently three cells at the opposite end. The latter have long been known as antipodal cells, but no particular function had .been ascribed to them. Ac- cording to more recent investigations, they very probably assist in the processes of nutrition. Strasburger's investigations gave us the most important results in regard to the nuclear divisions and fusions which result in the formation of the six cells mentioned and the secondary nucleus of the embryo-sac (see Fig. 132).* One of the three cells near the micropyle takes ujd the role of the egg-cell. The other two, which are known as the synergidce, are supposed to assist in the process of fertilization. From the observations. 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 ori
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectplants, bookyear1896
