Notes on Floridem. By George Massee. 563 



characteristic of the Floridees, are not developed, its true position is 

 uncertain. For the same reason the genera Choreocolax and 

 Pseudoblaste of Reinsch,* consisting of minute red filaments 

 parasitic on or among the tissue of other algae, are passed over, 

 since it does not follow that every red or pink seaweed belongs to 

 the Floridese ; hence Chantransia, from a morphological point of 

 view, stands at the base of the group. 



Harvey t divided algae into three primary groups, Chloro- 

 spermew, Melanospermete, and Bhodospermete, distinguished by 

 colour, the first being green, the second olive-brown, and the third 

 various shades of red or purple. This method of classification has 

 been entirely superseded by one which is almost entirely carpo- 

 logieal ; the structure of the organs of reproduction and fruit 

 being considered of primary importance in determining the position 

 of a plant in the system. The adoption of this later method has 

 'resulted in the entire rearrangement of the Chlorospermete and 

 Melanospermete. The Bhodospermete still remain intact, but are 

 now known as Floridew, an older name than Harvey's, used by 

 Agardh, and characterized by the presence of a more or less 

 elongated filament called the triehogyne, which is the attenuated 

 continuation of a cell known as the triehophore. When the 

 motionless antherozoids are passively floated in contact with the 

 trichogyne, they adhere to it, and fertilization takes place, followed 

 by the formation of spores, either in the triehophore, or more 



arranged lateral branches, the whole resembling a feather-veined leaf. In this 

 species the membrane is continuous, no space being left between the lateral 

 brandies, as in Ptilosa phimosa, fig. 21. Natural size. 



Fig. 25. — D. alata Lamour. Surface view of growing point. Neglecting for the 

 moment the membranaceous portion of the frond, we find a well-developed apical 

 cell a, but of the type characteristic of the' lower filamentous forms. For some 

 distance behind the apex, the axis is composed of a single row of superposed 

 cells, each axial cell giving origin to a pair of opposite monosiphonous branches ; 

 this arrangement recalls to mind such filamentous forms as CaUithamnion pluma 

 and C.plumula. Further back, the axial row is segmented into axial and peri- 

 central cells 6, or the Polysiphonia type is reached. At first the axial cells are very 

 short, but as they elongate, the lateral branches are not separated but remain 

 organically connected, and by cell-division give origin to the membranous portion, 

 at the same rate of increase as the elongation of the axial cell. The first septa 

 that appear in connection with the development of the membrane, are parallel to 

 the axis of growth of the branch, and cut the single superposed row of cells of 

 which it before consisted, into a posterior and an anterior row. The posterior 

 row, by repeated cell-division, form the membrane, which when fully developed, 

 consists of small polygonal cells ; the anterior row of cells generally undergo no 

 further division, but increase in length as the thallus becomes broader, so that 

 they eventually appear as long narrow cells forming the lateral " veins " which 

 are in the older portions, like the axis, cut into axial and pericentral cells d. The 

 apical cell of each lateral " vein," by segmentation, adds to its length c, x 300. 



* ' Contributiones ad Algologiam et Fungologiam,' 4to, Norimbergii, 1874-5. 

 f ' Nereis Boreali-Americana, ' 4to, New York, 1858. 



2 r 2 



