26 



BOTANY. 



There are very many examples of these simple Confervacece, 

 some like Conferva being simple rows of cells, others like 



Stigeodonium (Fig. 

 14, A), Chcetophora 

 and Drapamaldia 

 (Fig. 14,^,0), very 

 much branched. The 

 two latter forms are 

 surrounded by mass- 

 es of transparent 

 jelly, which some- 

 times reach a length 

 of several centime- 

 tres. 



Drapamaldia, x 50. C, a piece of Drapamaldia, 

 x 2. D, part of a filament of Conferva, x 300. 



FIG. 14. ConfervacesB. A, Stigeodonium. 



Among the ma- 

 rine forms related 



to these may be mentioned the sea lettuce ( Ulva), shown in 



Figure 15. The thin, bright-green, leaf-like fronds of this plant 



are familiar to every seaside student. 



Somewhat higher than Cladophora, 

 and its allies, especially in the differ- 

 entiation of the reproductive parts, are 

 the various species of (Edogonium and 

 its relatives. There are numerous 

 species of (Edogonium not uncommon 

 in stagnant water growing in company 

 with other algae, but seldom forming 

 masses by themselves of sufficient size 

 to be recognizable to the naked eye. 



The plant is in structure much like Clado- 

 phora, except that it is unbranched, and the 

 cells have but a single nucleus (Fig. 16, E). 

 Even when not fruiting the filaments may usually be recognized by pecu- 

 liar cap-shaped structures at the top of some of the cells. These arise as 

 the result of certain peculiarities in the process of cell division, which are 

 too complicated to be explained here. 



FIG. 15. A plant of sea 

 lettuce (Ulva). One-half 

 natural size. 



