CHAPTER III. 
FRESH-WATER ALG, 
a|N these days of popular science, when the 
most abstruse subjects come to us in 
~ forms as light and easy as the whisper- 
ings of confidential friends, or the chit-chat of the 
family circle, no department of natural history is 
more extensively and successfully studied than 
that which relates to the alge or sea-weeds. And 
. this need not be wondered at, for there is no class 
of plants more interesting, whether we regard the 
beauty of their colours, the gracefulness and variety 
of their forms, or the romantic situations in which 
they occur. The invention of that elegant orna- 
ment of the parlour and drawing-room, the aqua- 
rium, now so popular, has afforded great facilities 
for the study of these plants, under conditions and 
circumstances closely analogous to those of their 
native haunts; and much insight has: in conse- 
