. Text-book of botany, morphological and physiological. Botany. 3°s THALLOPHYTES. the enveloping tubes does not begin till a later period; the coils become gradually flatter while the apical cell of the branch increases considerably in size and developes into the oosphere (Fig. 199). The development and fertilisation of the carpogonium of Char a has recently been described in detail by De Bary in the case of C. fcetida. Here also it consists, from an early stage of its development, of an axial row of three cells, and five others consisting each of two cells which form an envelope round it. The
. Text-book of botany, morphological and physiological. Botany. 3°s THALLOPHYTES. the enveloping tubes does not begin till a later period; the coils become gradually flatter while the apical cell of the branch increases considerably in size and developes into the oosphere (Fig. 199). The development and fertilisation of the carpogonium of Char a has recently been described in detail by De Bary in the case of C. fcetida. Here also it consists, from an early stage of its development, of an axial row of three cells, and five others consisting each of two cells which form an envelope round it. The lowermost cell of the axial row is the nodal cell, the second remains small and colourless, and corresponds to the first ' Wendungszelle ' in Nitella. It becomes in this case also, as De Bary's drawings show, separated by a somewhat oblique septum at the base of the apical cell (now the third of the axial row). Originally almost hemi- spherical, the apical cell grows first of all into the form of a narrow cylinder, and then becomes ovoid; it is provided, until it attains its full size, with a thin very delicate cell-wall. Drops of fat and starch grains accumulate in its protoplasm: its apex however remains free from these, and forms a transparent finely granular terminal papilla, the receptive portion. The protoplasm of the apical cell of the carpogonium has therefore become transformed into an oosphere. The five enveloping tubes are from the first in close contact with the apical cell; after each has become divided by. Fig. 202. Development of the carpogonium of Nitella Jlexihs (x about 300); x ' a septum about half way up, the uppermost of the cells thus separated also become closely united with one another above the oosphere. This closing of the envelope takes place at least in Chara faziida, before the ' Wendungszelle' has separated from the oosphere. The five upper cells of the envelope are at first as long as the five lower ones, and the septa which sep
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1882
