148 NEMATOPHYCER. 
Famity V. GDOGONIACEA. 
Monecious, or dicecious alge. Filaments articulated, either 
simple (dogonium) or branched (Bulbochete). Basal cell 
obovate-clavate, mostly lobately divided, or ending in a disc. 
Propagation by zoospores, or by oospores after sexual fecunda- 
tion. The zoospores formed singly in certain cells, broadly oval 
or globose, transparent at one end, and furnished with a crown 
of vibratile cilia. Oogonia single or in a chain (2 to 5) con- 
tiguous to each other, more or less tumid, with a single oospore 
in each, becoming reddish brown or yellowish when mature, 
and then, before germination, dividing into (mostly 4) 
zoospores. 
Male plants, dwarf (nannandrous) and attached to the female 
plants, or elongated (macrandrous) and similar to the female 
filaments (often rather thinner). Spermatozoids produced in 
abbreviated special cells (spermogonia). 
Genus 64. C2DOGONIUM. Link. (1820.) 
Articulated filament simple, at first fixed, afterwards free 
swimming. Cells marked with transverse striw at one or other 
extremity. Terminal cell sometimes elongated and setiform. 
Either monecious or dicecious ; when diccious the male plants 
either dwarf—produced from short cells of the female plants— 
or elongated and independent. 
Propagation by asexual zoospores, and by oospores sexually 
fertilized. 
For details of the structure and reproduction, consult “ Braun on 
Rejuvenescence” (Ray Society, 1853). “Pringsheim Jahrbucher” 
(1857). “Quarterly Journal of Microscopical Science,” vi. new series, 
1866, p.149. De Bary, “ Aidogonium und Bulbochete” (1854). Juranyi 
in Pringsheim “ Jahrbucher” (1873). Carter, in “Annals of Natural 
History,” 3 ser. i, p. 31. Vaupell, ‘‘ Jagttagelser ov. befrugt. Cidogo- 
nium” (1859). Wood, “ Fresh Water Algz of the United States” (1872), 
Wittrock, ‘ Prodromnus Monographise @idogoniearum” (1874). 
The sterile filaments of Cdogonium resemble those of Crnferva at a 
casual! glance, but are soon seen to be distinguished by transverse parallel 
striz at one or other extremity of many of the cells. These strise are 
indications of the mode of cell increase (Pl. LVII, fig. 5) which takes 
place in the following manner:—When a cell has reached maturity, and 
is about to divide, a little circular line is seen near its upper -end. 
Gradually the line widens, and it is seen that the wall of the mother 
cell has divided all round, and the cell above is slowly raised by the 
growth of the daughter cell, arising, as it were, out of the apex of its 
parent cell, and carrying upwards the first streak or cap left by the 
