THALLOGENS. 99 



some species may present many points of resemblance 

 with the simple Protophytes. 



3. The ALG^E, or Sea-weeds, have been divided into 

 three orders, the Red, the Olive, and the Green Sea- 

 weeds Rhodospermeae, Melanospermeae, and Chloros- 

 permeae. " The latter order generally includes the Con- 

 fervoid and other families which we have considered as 

 unicellular plants. When we examine the higher Sea- 

 weeds, we find a certain foreshadowing of the distinction 

 between Root, Stem, and Leaf, which is characteristic 

 of still higher types. This sort of unconscious prophecy 

 of higher forms to come is by no means uncommon in 

 other classes both of plants and animals, and affords 

 another proof that living things have been formed on 

 an intelligent plan. In the Sea-weeds, however, the 

 apparent distinction of stem and root serves for little 

 else than the mechanical attachment of the plant. There 

 is no departure from the cellular type, the only modifi- 

 cation being that the layers of cells are of different sizes 

 and shapes. 



4. The Olive Sea-weeds, or Fucoids, (Melanospermce^ 

 often grow to a considerable size, attached by sucker-like 

 roots to the rocks, and, in some cases, buoyed up by air- 

 bladders. Others are parasitical. The fructification of 

 many species in this group is sexual. In the common 

 bladder-wrack, Fucus vesiculosus, the reproductive organs 

 are on different plants, but in other species, as Fucus 

 senatus, they are both together, the one olive-green, the 

 other orange-yellow. The " receptacles " are at the ex- 

 tremities of the fronds, and may be known to be mature 

 by each discharging little gelatinous masses adhering- 



