52 
FUCACEiE. 
IV. 
puscle is always in front ; while the cilium, rising from the coloured granule, 
trails behind like a tail. 
Messrs. Decaisneand Thuret, from whose memoir (in Ann. des Sc. Nat. 1845, p. 5 
et seq.) this description is mostly taken, point out the strong analogy between these 
vivacious corpuscles of the Fucacece and the so-called spermatozoa of the Characeae, 
Mosses, and Hepaticae, and argue from this similarity of structure a similarity of 
function. They are, therefore, of opinion that the corpuscle-bearing cells are 
properly organs of a similar nature to the antheridia of other cryptogamic plants ; 
and not, as is supposed by Agardh, analogues of the sporidia of the lower Algae, 
and like them capable of germination. From my own investigations, I am disposed 
to agree with the opinion which regards them as male organs. They may readily 
be seen with the higher powers of the compound achromatic microscope ; and are 
easily found in the ordinary shore Fuci, ( Fucus vesiculosus and F. nodosus), in 
winter or early spring, on specimens bearing bright yellow or orange coloured 
receptacles. Some of the most deeply coloured should be selected and placed in the 
air till partially dry. As the frond dries, little drops of a slimy, bright orange fluid 
will ooze out from the pores of the receptacle; and if one of these drops be removed, 
and placed in a little sea water on the stage of the microscope, it will be found to 
consist of multitudes of detached antheridia. If these be watched for a short time, 
the vivacious corpuscles may be seen to issue from them and perform their singular 
dances. 
The Fucacece are readily known from all other orders of Melanosperms, by 
having their spores contained in those little spore-cavities, which we have already 
described. In no other order do such cavities exist. 
The group of plants defined by this character is a very extensive one, comprising, 
perhaps, one-half of the known Melanosperms. If we view it as also composed of 
an aggregate of individuals of each species, its relative importance will appear 
very much greater, for most of the plants of which it consists are social ones, and 
clothe very large portions of the submarine soil. About 230 species are described 
by Agardh in his last work, while Kiitzing, (who has introduced many species 
which are not admitted by other writers) enumerates upwards of 300. Of this 
large number, however, I am only able to claim 20 as inhabiting the American 
shores, and six of these are known only on the Pacific coasts. 
The deficiency of Fucacece is a very remarkable feature of the American marine 
flora, the common fuci of the eastern coasts being only two, ( Fucus vesiculosus 
and nodosus ) and these two scarcely growing south of New Jersey. No doubt the 
long line of sandy shore which extends from New York Bay southward forbids 
the production of plants whose natural habitat is on tidal rocks and boulders ; 
but it is remarkable that on the rock-bound coasts of the North Eastern States, 
there is no trace of the Fucus serratus or F. canaliculatus which are so widely dis- 
persed on the European side of the Atlantic. We should not consider this absence 
of common European forms remarkable, if the Fuci found on the American coasts 
were peculiar to them. It is because the two species so abundant in America are 
also common in Europe, that we wonder at the absence, in the western waters of 
the Atlantic, of the equally common forms with which they are associated in the 
eastern. 
