324 VEGETABLE ORGANOGRAPHY. 



attached, as Fucus vesiculosus, by a small part of the 

 base which adheres to solid bodies, but we know not by 

 what kind of mechanism this takes place. Sometimes 

 they lay hold of projecting and angular parts by kinds of 

 root-like cramps, as Fucus saccharinus : this organization 

 especially takes place in the large species, which are 

 liable to be detached by the shock of the waves of the 

 sea ; but these cramps do not perform, as to the absorp- 

 tion of juices, any function which is not common to 

 the whole of the tissue. 



The foliaceous parts are often traversed by nerves 

 resembling in appearance those of ordinary leaves, being 

 frequently pinnate as they are, but they are only com- 

 posed of elongated cellular tissue. They are commonly 

 also entirely devoid of nerves, as in Ulva. There are 

 some which seem to be only composed of isolated 

 cellules full of juice ; such is, in particular, Protococcus 

 nivalis, or that singular production, of a red colour, 

 which grows on the snow at the Pole, and on the 

 Alps. 



They are frequently composed, like most plants of 

 their class, of a great number of cellules, wliich form a 

 thick tissue. We can even distinguish in the Florideae 

 and several Fucacese a kind of bark, formed of round 

 cellular tissue, distinct from the centre, which is of a tissue 

 either elongated, or more compact, and having the ap- 

 pearance of a woody body. Sometimes the cellules are 

 all disposed in a single series, whence results sometimes 

 a foliaceous lamina, very thin, and truly membraniform, 

 as that of the Ulvae ; sometimes very slender filaments, 

 all formed of cellules placed end to end, as in certain 

 Confervse. 



The Confervse have often been spoken of in botanical 

 works as formed of articulated filaments ; it is necessary 

 to remark here that this name is not correct, and it ought 



