CRYPTOGAMOUS OR FLOWERLESS PLANTS. 503 



the trunks of the tallest forest-trees, while others have leaves 

 (fronds) which rival in expansion those of the Palm." " Others 

 again are so minute as to be wholly invisible, except in masses, to 

 the naked eye, and require the highest powers of our microscopes 

 to ascertain their form and structure." Some have the distinction 

 of stems and fronds ; others show simple or branching solid stems 

 only ; and others flat foliaceous expansions alone (Fig. 82), either 

 green, olive, or rose-red in hue. From these we descend by suc- 

 cessive gradations to simple or branching series of cells placed end 

 to end, such as the green Confervas of our pools, and many marine 

 forms (Fig. 81) : we meet with congeries of such cells capable of 

 spontaneous disarticulation, each joint of which becomes a new 

 plant, so that the organs of vegetation and of fructification become 

 at length perfectly identical, both reduced to mere cells ; and 

 finally, as the last and lowest term of possible vegetation, we have 

 the plant reduced to a single cell, giving rise to new ones in its 

 interior, each of which becomes an independent plant (94-99). 



947. The fructification of Algae exhibits four principal varieties. 

 In the great division of olive-brown or olive-green proper Sea- 

 weeds, the MELANOSPERMEJE of Harvey, the fructification forms tu- 

 bercles immersed in the tissue of the summit of the branches of 

 the frond (Fig. 1188-1191), which are filled with a mass of sim- 

 ple spores with filaments intermixed (1191), invested by a proper 

 membranous coat, and finally escaping from the frond by a minute 

 orifice. The beautiful red -colored Seaweeds, or RHODOSPERMEJE, 

 exhibit two kinds of spores ; one large, simple, superficial, and re- 

 sembling those above described, except that they have no proper 

 integument ; the others, dispersed through the interior of the frond, 

 are formed fou? together in a mother cell. The bright green se- 

 ries, or CHLOROSPERME.&, have the whole green contents of certain 

 cells, or of some part of the cell, (as in Vaucheria, Fig. 71, 72, 

 467, and in Conferva vesicata, Fig. 474, &c.,) condensed into a 

 spore, in some of the ways already described (95-101), or else 

 they result from the conjugation of two cells (102, Fig. 78-81). 

 This conjugation occurs throughout in the 



948. Sllbord, Desmidiese, which are microscopic and infusory green 

 Algse of single cells (Fig 77-80) often of crystal-like forms, in- 

 vested with mucus, and belonging to fresh water. They multiply 

 largely by division, but propagate only by conjugation. Many of 

 them have long been claimed for the animal kingdom, or esteemed 



