CEDOGONIUM. 67 



Plate LXXIII, fig. 1, filament of a female nannandrous plant 

 with oogonium and nannandres or dwarf males. Figs. 2, 2, 3, 3, 

 parts of filaments with transverse striae indicating the mode of cell 

 multiplication peculiar to this genus. When a cell has reached 

 maturity it splits immediately below the apex by a circular line 

 around the cell and by growth the top is raised and a new cell 

 formed ; this new cell may split again as before, below the apex, 

 the top be pushed up by the growth of another cell, leaving two 

 transverse striae The same process is often repeated five, six, 

 or more times and thus producing as many stria?. Fig. 4, 

 section of filament of a female alga showing androsporangia 

 (fig. 5), and dwarf males, (figs. 18, 19). Fig. 6, female mono3cious 

 plant with spermogonia cells ( fig. 7 '), hypogynous ; and oogonium 

 with pore in superior part of it. Fig. 8, filament of monoecious 

 plant with spermogonia cells which are hypogyuous, (fig. 9); sub- 

 hypogynous, (fig. 10) ; epigynous, (fig. 11) ; subepigynous, (fig. 

 12); and apical, (fig. 13); pore of oogonium, (fig. 14), open cen- 

 trally. Fig. 15, a male plant with androsporangia cells, (fig. 16). 

 Fig. 17, androspores escaping. Fig. 18, dwarf males, stipe, 

 and spermogonia (fig. 19), bicellular. Fig. 20, zoospore making 

 its passage out of mother cell. Figs. 21, 22, 23, fully developed 

 zoospores, furnished with cilia? and becoming very active. Figs. 

 24-26, zoospores come to rest and developing young plants. 

 Figs. 27-30, advancing stages of development. Figs. 31-33, 

 imperfect zoospores passed out of cell through a fissure and ad- 

 hering. Fig. 34, an oospore surrounded by a multitude of active 

 spermatozoids (!). Fig. 35, shows how some oogonia, destitute 

 of pore, open by an operculuin or lid. Figs. 36, 37, oospore 

 passing out of oogonium. in a vegetative plant. Figs. 38, 39, 

 clusters of young plants, found on an entangled mass of old Oedo- 

 gonium in a water trough, which was dotted with small radiating 

 clusters barely visible to the unassisted eye ; many very small, 

 others larger, containing each from ten to fifty shorter or longer 

 radiating filaments in character the same as the mother, or older 

 plants ; could not satisfy myself whether these clusters spring from 

 gonidia breaking through the cell walls (compare Plate LXXXIII, 

 fig. 6), or from oospores breaking up into niicrogonidia. The 

 figures represent two clusters, like which there were hundreds 

 seen under very low magnification. The old forms were identi- 

 fied as Oe. pachyandrium, Found October, 1882. 



