Our Fresh-Water Alge. 677 
Francis Wolle, there is perhaps but one which has an odor remark- 
ably offensive : this, the Hydrurusis, however, so unpleasant that the 
Dane Lyngbye remarked of it seventy years ago that “it could be 
endured only by an algologist.” Bory called attention early in 
this century to “the most peculiar odor” of Lemanea when burned. 
Extend the view to the Charas, and to the diatom Schizonema, and 
a number of species of imitating or unpleasant odors are met; but 
the number of algz which are in themselves possessed of much odor 
ofany kind is few. If any persons associate disagreeable odors with 
the alge, it is doubtless from confusing the odor of a place with 
that of an alga happening to be at the time its resident. Nor are 
the alge without examples of exquisite fragrance ; man might not 
have thought to look here for the sweetest odor, but Nature has not 
forgotten to add that charm to some of these, her lowly children ; 
one of them Chrodlepus odoratus, has been known in Denmark for 
over seventy years as the “sweet conferva”; it grows also on the 
bark of shade trees along highways in Pennsylvania. Perhaps 
more interesting still is the fragrance of the violet-moss, Chrodlepus 
iolithus, which attracted the attention of Linnzeus almost a century 
and a half ago; it grows asa thin glaucous, green or reddish- 
orange layer over stones in the Alps and in our own country in the 
White Mountains, causing them to “give forth a strong odor of 
violets.” The Swiss are said to earry these stones home and by 
occasional moistening, to renew the odor from time to time. These 
Alpine people call it “Veilchen-moos ” and the“ Veilchen-stein ” ; 
and this latter was adopted as its name in science by Linneus, for 
the specific name he gave it and which it still bears, is to be trans- 
lated Violet-stone. 
The size of our fresh-water algæ has been already referred to as 
commonly microscopic ; yet there are many of considerable dimen- 
sions. About Washington we have Tetrasporas growing a foot long, 
beautiful undulating sheets of translucent green floating out on 
flowing water; some of our Cladophoras are still longer ; and the 
sac-like Water-nets and the string-like Conferve equal or exceed 
them, Any locality may yield however, for one specimen of six 
Inches, a score of but one inch, and for each of the latter, an 
equally increased proportion on or below the border-line of vision. 
Many minute algæ become very conspicuous by reason of their 
