. Carnegie Institution of Washington publication. 92 FECUNDATION ; HETEROGAMETES. of which only one is borne in each antheridium, are, according to Pringsheim ('58, p. 297), almost entirely colorless, with but a faint greenish hue; each bears at the anterior end two cilia, one extending backward during the progressive motion of the cell. In the absence of a chromatophore the spermatozoid of Coleochcete differs from that of CEdogonium, in which the chlorophyll undergoes a transformation in the male gametes, and in this respect it foreshadows the develop- ment of the sperm in higher plants. The
. Carnegie Institution of Washington publication. 92 FECUNDATION ; HETEROGAMETES. of which only one is borne in each antheridium, are, according to Pringsheim ('58, p. 297), almost entirely colorless, with but a faint greenish hue; each bears at the anterior end two cilia, one extending backward during the progressive motion of the cell. In the absence of a chromatophore the spermatozoid of Coleochcete differs from that of CEdogonium, in which the chlorophyll undergoes a transformation in the male gametes, and in this respect it foreshadows the develop- ment of the sperm in higher plants. The oogonium is also developed from the end cell of a branch. It is recognized first by the presence of a beak at the distal end of the cell, which soon becomes the neck of the flask-shaped organ (Fig. 32, C, D). In the neck dense colorless cytoplasm accu- mulates which contains one or more large vacuoles. In the basal or ventral portion are sit- uated the nucleus, a large vac- uole, and a laterally placed chloroplast. The neck now increases in length with an ap- parent increase in the quantity of its cytoplasm, the ventral portion remaining unchanged. As soon, however, as the neck FIG. 32,-Development of sexual organs in Coleochate has reached its definitive size, 3 pulvinata.—(After Oltmanns.) A, B, development of antheridium. transformation takes place in c, D, two young stages of the oGgonium. tiie ventral part of the oogo- nium ; the chloroplast leaves its lateral position, passes down and applies itself closely to the bottom of the organ (Fig. 33, E). It has increased appreciably in size and contains two pyrenoids. The oogonium opens probably by the gelatinization of the end wall of the neck. As soon as the organ opens the cytoplasm contracts into the basal portion to form the egg-cell. Whether a part of the cytoplasm in the neck is thrown off cannot be stated positively, but there is no reason to believe that this occurs. Both Jost and Oltmanns accord in the opinion that n
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