D e s f o n t a in e s , Baron W u l f e n , W e b e r and M o h r , G r a t e -
L o u p , Professor M e r t e n s , termed by Weber and Mohr the
most able algologist of their time, V a u c h e r , L in k , J ü r g e n s ,
and M. C h a u v in . M . J ü r g e n s has published Fasciculi of
dried specimens of Algoe from Jever and the coast of East
Friesland. And my friend M. C h a u v in of Caen (Keeper of
the Museum of N atural History), is engaged upon a most useful
work of a similar nature, containing the Algoe of Normandy,
four or five fasciculi of which have made their appearance.
Like the great natural groups of Lichens, Mosses and
Ferns, the Marine Æi/æ, or, as they are popularly denominated,
Sea-weeds, have a wide geographical range. To a considerable
extent they seem to obey the same laws as the higher
orders of vegetable forms. B u t it is doubtful if we are at
present acquainted with all the agents which influence the
growth of plants in a medium so different from air as th a t of
water. The very existence of Botanical Geography as a
science, is of recent origin ; and though the labours of such
men as H u m b o l d t , B r o w n , W a h l e n b e r g , B e C a n d o l l e ,
ScHOUW and others, have reduced it to form, and established
some of its leading principles as far as the ordinary vegetation
of the earth is concerned, little has been done for the
cryptogamie tribes. The distribution of the Marine Algoe
engaged the attention of the late Professor L a m o u r o u x ,
whose essay upon the subject was published posthumously,
in the seventh volume of the Annales des Sciences Naturelles.
M. B o r y d e S t V in c e n t has also added some observations,
h u t mixed up with a good deal of extraneous matter, in the
botanical p a rt of D u p e r r v ’ s Voyage round the world _
I t is very clear, and well known to the practical botanist,
that marine plants are much influenced by the nature of the
soil, not merely in regard to species, h u t in luxuriance and
rapidity of developement. A few yards is in some instances
sufficient to create a change, and the space of three or four
miles a very striking one. Thus, calcareous rocks favour the
production of some species, sandstone and basalt that of
others; and it would appear th a t the soil has an effect even upon
those Algae which grow parasitically upon the stems of the
larger species. Bu t sometimes, to all appearance independently
of this cause, peculiar forms predominate in certain
localities, both in regard to genera and species, which, as we
approach their boundaries, gradually disappear, and often give
place to others equally characteristic.
Pluenogamous plants have furnished botanists with several
grand vegetable regions, and a marked difference (not to specify
more examples) has been recognised between the plants
of America, Africa, Asia, Australia, and Europe. L a m o u r
o u x endeavoured to trace these great divisions among marine
plants, and observed th a t the polar Atlantic basin, to the
fortieth degree of north latitude, presents a well-marked vegetation.
The same may he said of the West Indian sea, including
tlie Gulf of Mexico—of the eastern coast of South America—
of the Indian Ocean and its gulfs, and of the shores of
New Holland, and the neighbouring islands. The Mediten-a-
nean possesses a vegetation peculiar to itself, extending as far
as the Black Sea, and notwithstanding the geographical proximity
of the port of Alexandria and the coasts of Syria to
those of Suez and the Red Sea, the marine plants of the former,
in regard to species, differ almost entirely from those of
the latter. B o r y d e S t V in c e n t characterizes each of his
Mediterranean Seas hy a vegetation different from that of the
Arctic, Atlantic, Antarctic, Indian, and Pacific Oceans, and,
to a certain extent, lie is probably correct, as such seas are of
less depth, often of a higher temperature, and more directly
influenced hy the countries which more or less enclose them.
The seas which, he considers as Mediterranean, are the Mediterranean
properly so called, the Baltic Sea, the Red Sea,
the Persian Gulf, the Chinese Sea, the Seas of Okhotsk and
Bhering, and the West Indian Sea, along with the Gulf of
Mexico, denominated hy him The Coluinhian Mediterranean.
Every great zone presents a peculiar system of existence :
and it is said, th a t after a space of twenty-four degrees of latitude,
a nearly total change is observed in the species of or