16 MARCUS M. HARTOG. 
CoLEOCHATEZ are also oogamous ; the oosophere essentially 
resembles that of Oedogoniee, but it is the direct trans- 
formation of a superficial tissue-cell: its fertilising beak is 
prolonged into a slender tube open at the apex, the “ Tri- 
chogyne ;” the formative cytoplasm contained therein de- 
generates as in Oedogoniex, while the rest of the proto- 
plasm in the body of the oogonium rounds off into the oosphere. 
The spermatogonium undergoes two binary divisions, and 
the cell-body of each of the cells so formed escapes as a bifla- 
gellate spermatozoon. In certain species the four daughter- 
cells of the spermatogonium are budded off at its apex, and 
though no information has been given we may well believe 
the process to be that following as found in the spore forma- 
tion of Basidiomycetes. The nucleus of the basidium divides 
by two mitoses, and each of the four nuclei so formed migrates, 
accompanied by cytoplasm, into a bud formed at the apex, 
which becomes shut off by a septum from the now sterile and 
enucleate basidium.! That we are fairly justified in interpreting 
budding here as a modification of segmentation is obvious when 
we reflect on the behaviour of meroblastic ova or the zygote 
of Noctiluca (infra, p. 41) in their segmentation. 
In the MeLanornyce@, or Olive Seaweeds, we have seen the 
transition from isogamy through anisogamy to hypoogamy. 
True oogamy occurs in the highest order of this group, the 
Fucaceam.” In these the oogonial nucleus divides by succes- 
sive mitoses into eight gametonuclei. In Fucus each of 
these attracts round it one eighth of the cytoplasm, so that 
there are eight oospheres. In Ascophyllum four of the 
nuclei pass to the centre, and four lie at equal distances nearer 
the surface of the cytoplasm. The cytoplasm aggregates 
around the four peripheral nuclei to form four oospheres, 
leaving the four central nuclei as rejection-bodies in the 
1 Possibly, however, the formation may take place as in the Floridian genus 
Chondria (infra, p. 30). 
2 The following account is taken from Oltmanns’ “ Beitrage zur Vergleich. 
Entwicklungsgesch. der Fucacee,” in ‘ Sitzungsber. d. Berlin Akad.,’ 1889, 
p. 587. 
