676 Our Fresh-Water Alge. 
the Charas secrete instead of silica, a sheath of carbonate of lime 
about themselves, until the whole plant seems a succession of joints 
of stone, or links of white lime, giving it its popular cognomen of 
stonewort. 
The colors of our fresh-water alge are varied to a degree that 
may surprise the student who expects only green. There is consid- 
erable variety even in their green, from the usual grass-green of the 
Spirogyras to the pea-green of some Palmellas ; the little “ water- 
flower,” so to render its name, Anabcena flos-aquee, is a verdigris- 
green ; Chlamydomonas hyalina is called by Wolle a milky-green- 
Many shades of red are found, vermilion in Chlamydococcus, scarlet 
in Thorea, blood-red in Glaocapsa sanguinea, amethystine in Lepto- 
thrig tinctoria; Hildenbrandtia is often purple, one of the Chantran- 
sias is rose-purple, a Lemanea is violet ; species of Chrodlepus range 
through ash, yellow and orange to golden-red ; Tuomeya is said to 
be olive-colored, Hydrurus ochre ; some Vaucherias are brown, one 
Gleocapsa is black ; a Leptothrix is straw-colored, another fawn, 4 
Chantransia steel-blue, a Cylindrocapsa pearly. Many preserve their 
color when dried; others change, some simply by fading to 4 
lighter shade of their previous color, others to a new tint; one 
Batrachosperm is described as at first of a mouse-gray color, then 
yellow, and on drying, violet ; Chantransia macrospora and Thorea 
are, when living, dark green, but dry a beautiful purple-violet ; the 
Sweet Chroolepus is tawny when fresh, changes to an ashen-gray an 
finally greenish ; a kindred species is reddish-orange when olive, 
light yellow on drying ; Zygnema purpureum changes from yellow- 
ish-green to dark purple; Lyngbya tinctoria, says Wolle, from 
purple to violet steel; Vaucheria dichotoma may stand as type of 
the change so frequent in the higher plants, from green to brown- 
Many alge unite several colors at the same time ; almost all do so 
when we compare the spores with the vegetative growth ; a remark- 
able instance of variegation in vegetable growth alone is seen 1m 3 
new Lyngbya found by Wolle in the Lehigh at Bethlehem, 
Pennsylvania, waving in tufts six inches long, “ the one 
bright-blue green, lower parts changing to yellow-brown ; and @ 
last fading out to a colorless base.” 
Few of the odors possessed by the alge have received a name 
Out of the 1300 species recorded in this country by the Rev. 
