136 SYSTEMATIC BOTANY. 



leave iotercellnlar spaces. There is also considerable 

 difi'erentiation into reproductive organs, somewhat analo- 

 gous to the floral branches in the higher plants. The repro- 

 ductive organs, that is, oogonia and antheridia, are borne 

 on modified branches, which diflfer more or less from the 

 ordinary ones; they are generally contained in hollows 

 (called coneeptacles) of the epidermis. Some species are 

 moneecious ; others, dioecious. No non-sexual reproduction 

 takes place. While most Thallophytes are short-lived, the 

 plants of this group often live many years. The species 

 of Fucus and Sarffagsum are washed ashore in great quanti- 

 ties and used as a fertilizer for soil, and also for obtaining 

 alkalies and iodine. Sarffagsum bacdferum is the Gulf- 

 weed, which covers a large area in the Atlantic, called 

 the Sargasso Sea. 



CARPOSPORE^. 



170. The fourth division of the vegetable kingdom, 

 viz. the Carposporeae, is characterized by the produc- 

 tion of a sporocarp, which consists in general of two 

 parts: (1) a fertile part, which directly or indirectly 

 produces the spores ; and (2) a sterile part, which is com- 

 posed of cells or tissue developed from the cells adjacent 

 to the fertile part and envelopes the latter. Some of the 

 representatives are chlorophyll-bearing, as the Bed Marine 

 Algse ; others are destitute of chlorophyll and parasitic, as 

 the Wheat Eust, Corn-Smut, etc. ; or saprophytic, as the 

 Toad-stools and Puff-balls. In the higher members of the 

 group there is a considerable differentiation into ea/ulome 

 (or stem) and phyllome (or leaf). The non-sexual repro- 

 duction may take place by the production of (1) zoospores, 

 (2) non-motile tetraspores (so called because they are 

 mostly formed by the division of the mother-cell into 



