BOTANICAL SUBJECTS. 



249 



To recapitulate then, the frond of this Sargassum (Fig. 92) 

 is essentially what one might call a bipinnate cladophyl, the leaf 

 proper of phaenogams being only a further modification of some 

 such ancestral form. This cryptogam in its frond ha« a main 

 midrib (the stem) and sub-divisional midribs (the leaves). It has 

 flower racemes, emerging from the petioles of the pinnae close 

 to their axillae. Then each flower spikelet or spore receptacle is 

 subtended by a bract-like frond. What more is needed to prove 

 their homology with similar organs in phaenogams ? And what 

 more is needed than infinite reproduction, and consequent keen 

 selection tlirough ages of time, for these simpler vegetable forms 

 to emerge out of water, and on dry land be transformed into the 

 innumerable forms of stem, leaf, and flower which we see 

 everywhere ? 



Fig. 9.5. Sargassum lacerifolium, Ag.,* showing float F. 



Moreover, Sargassum lacerifolium, Ag. (Fig. 95), besides a 

 similar inflorescence with bracts, shows that the vesicle which acts 

 as a float is only a bladdering of the petiole, as in Trapa natans 

 and others. 



I believe that among seaweeds we have many type forms of 

 existing j)hsenogams, from which, or from similar forms, it is not 

 unreasonable for an evolutionist to suppose that the latter may 



* PI. 208, « Harv. Phyc. Austr." 



