FLORIDE^ 



19.S 



.(Lnix.), and a few other genera, the 'frond' becomes densely incrusted 

 by a deposit of calcium carbonate, giving to the so-called 'corallines' 

 .the external form and appearance of miniature corals. 

 J The ordinary non-sexual propagative organs of the Floridese are 

 bright red motionless spores, commonly formed in fours in the mother- 

 jCell, and hence known as tetraspores (the sphaerospores of Agardh), arid 

 the cell in which they are produced as a.tetrasporange. The four spores 

 ■,are sometimes arranged in a row, when they are called zonate ,; more 

 often as quadrants of a sphere, when they are cruciate : rarely there are 

 only one or two, or occasionally eight. In-'thesUlvacese, Lemaneacese, 



Fig. iji.—Cmuama. attenuaia Ag. a, branch (x 40) ; i, apex of branch (x 100) ; c, lower ; 

 portion of branch with tetrasporanges(x 100). (After Kiitzing.) 



and in some Nemalieas they are altogether wanting. The tetraspores 

 (see' fig. 231) may be formed in the six following ways : — (i) The 

 whole contents of the sporange become a single spore ; (2) the contents 

 divide into two equal parts by a transverse wall ; (3) they divide into 

 four quadrants by two successive bipartitions ; (4) they divide into four 

 tetrahedra by simultaneous quadripartition ; (5) they divide into four 

 by three parallel transverse walls ; (6) the contents divide into more 

 than four spores. On germination the tetraspores may give birth either 

 to sexual or to non-sexual individuals. In the monosiphonous Florideae 

 the tetrasporanges are usually formed at the expense of the ultimate 

 branchlets. In other forms they are most commonly found scattered 



