g2 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 Coleochete differs from that 
of G@dogonium, 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 odgonium 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 
Fic. 32.—Development of sexual organs in Coleochete has reached its definitive size, a 
pulvinata.—(After Oltmanns.) mies 2 
A, B, development of antheridium. transformation takes place in 
C, D, two young stages of the odgonium. the ventral part of the obg0- 
nium ; the chloroplast leaves its lateral position, passes down and applies 
itself dicsely to the bottom of the organ (Fig. 33, E). It has increased 
appreciably in size and contains two pyrenoids. The odgonium 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 no 
cytoplasm is expelled when the odgonium opens, while Pringsheim 
speaks of the extrusion of a colorless substance only, which disor- 
ganizes at once, The expulsion of a small quantity of mucilaginous 
substance, or even cytoplasm, is utterly without important significance, 
as the nucleus of the odgonium does not divide previously to fecunda- 
