SECTION 17.] 



THALLOPHYTES. 



167 



their decay. True as these general distinctions are, it is no less true that 

 these orders run together in their lowest forma ; and that Alga and Fungi 

 may be traced down into forms so low and Bimple that no clear In..' can be 

 drawn between them ; and even into tonus of which it- is uncertain whether 

 they should he called plants or animals. It is as well to say that they are 

 not high enough in rank to he distinctively either the one or the other. On 

 the other hand there is a peculiar group of plants, which in simplicity of 

 OOmposition resemble the simpler AlgB3, while in fructification and in the 

 arrangements of their simple cells into stem and branches I hey seem to be 

 of a higher order, viz. : — 



506. Characeae. These are aquatic herbs, of considerable size, abound- 

 ing in ponds. The simpler kinds (Nitella) have the sicm formed of a 

 single row of tubular cells, and at the nodes, or junction of the cells, a 

 whorl of similar branches. Chara | Fig. 550-552) is the same, except that 

 the cells which make up the stem and the principal branches are strength- 

 ened by a coating of many smaller tubular cells, applied to the surface 



of the main or central cell. The fructifi- 

 cation consists of a globular sporocarp 

 of considerable size, which is spirally 



enwrapped by tubular cells twisted around it: by the side o\' this is a 

 smaller and globular antheridium. The latter breaks upintoeiglri slneld- 



Fio, 553. Aganun Tnrneri, Sea Colander (so called from tin- perforations with 

 which the frond, as it grows, becomes riddled); rery much reduced In 



Fkj. 664. Upper end <>r :t Rockweed, Fucus resiculosus, reduced half or more, 

 b, the fructification, 



