SECTION 17.] 



THALLOPHYTES. 



169 



a small orifice which in each figure is at the margin of the page. The large 

 spores are formed eight together in a mother-cell. The minute motile 

 iilaments of the antheridia fertilize the large spores after injection into the 

 water: and then the latter promptly acquire a cell- wall and germinate. 



510. The Floridese or Rose-red series of marine Algse (which, however, 

 are sometimes green or brownish) are the most attractive to amateurs. 

 The delicate Porphyra or Laver is in some countries eaten as a delicacy, and 



the cartilaginous Chondrus crispus has 

 been largely used for jelly. Besides their 

 conceptacles, which contain true spores 

 (Fig. 560), they mostly have a fructifi- 

 cation in Tetraspores, that is, of spores 

 originating in fours (Fig. 559). 



511. The Grass-green Algae sometimes form broad membranous fronds, 

 such as those of the common Ulva of the sea-shore, but most of them form 



^(T0qOo| 



mere threads, either simple or branched. To this division belong almost 



Fig. 557. Small plant of Chondrus crispixs, or Carrageen Moss, reduced in 

 size, in fruit; the spots represent the fructification, consisting of numerous tetra- 

 spores in hunches in the substance of the jilant. 558. Section through the thickness 

 of one of the lobes, magnified, passing through two of the imbedded fruit-clusters. 

 559. Two of its tetraspores (spores in fours), highly magnitiwl. 



■piG. 560. Section through a conceptacle of Delesseria Leprieurei, much magni- 

 fied, showing the spores, which are single specialized cells, two or three in a row. 



Fig. 561. A piece of the rose-red Delesseria Lepreinrei, double natural size. 

 r)62. A jiiece cut out and much magnified, sliowing that it is composed of a la}-er 

 Bf cells. 563. A few of the cells more highly magnified: the cells are gelatinous 

 »nd thick-walled. 



