148 NEMATOPHYCE^E. 



FAMILY V. OEDOGONIACEJE. 



Monoecious, or dioecious alga?. Filaments articulated, either 

 simple (CEdogoniuni) or branched (Bulbochcete). 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. CEDOGONIUM. Link. (1820.) 



Articulated filament simple, at first fixed, afterwards free 

 swimming. Cells marked with transverse stria* at one or other 

 extremity. Terminal cell sometimes elongated and setiform. 

 Either monoecious or dioecious ; when dioecious 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 " Brann on 

 Rejuvenescence" (Ray Society, 1853). " Pringsheim Jahrbucher" 

 (1857). " Quarterly Journal of Microscopical Science," vi. new series, 

 1866, p. 149. De Bary, " yEdogonium und Bulbochsete " (1854). Juranyi 

 in Pringsheim "Jahrbucher" (1873). Carter, in "Annals of Natural 

 History," 3 ser. i, p. 31. Vaupell, " Jagttagelser ov. befrugt. CEdogo- 

 nium" (1859). Wood, " Fresh Water Algaa of the United States " (1872). 

 Wittrock, " Prodrornus Monographic (Edogoniearuin " (1874). 



The sterile filaments of CEdogonium resemble those of Ccnferva at a 

 casual glance, but are soon seen to be distinguished by transverse parallel 

 striaa at one or other extremity of many of the cells. These striae are 

 indications of the mode of cell increase (PI. 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 



