FLORIDEyE. 133 



an apical cell, and in a branchlet destined to produce 

 antheridia from three to six cells at the base are developed, 

 after the manner of those of the ordinary vegetative branch- 

 lets, becoming about as long as broad when full-grown, and 

 not in any way divided. After the formation of these cells, 

 which constitute the stalk of the antheridia-bearing branch- 

 let, the remaining daughter-cells, to the number of ten or 

 more, immediately after their segmentation from the apical 

 cell, have four cells cut off by incurring septa from the 

 circumference. Each of these four cells again divides into 

 two by the formation of a radial septum, the result being 

 a central axial cell, surrounded by eight pericentral cells. 

 From the free surface of each pericentral cell two or more 

 minute papillae appear, which grow out for a short distance 

 as exceedingly slender tubes, and soon become swollen at 

 the apex; the swollen portion becomes cut off by a septum 

 from the cavity of the slender tube or stalk, and its contents 

 transformed into a single poUinoid. The entire develop- 

 ment is acropetal. At the base we find perfectly formed 

 antheridia ; higher up, the eight pericentral cells with rudi- 

 mentary papillje ; still higher, only four pericentral cells, and 

 at the apex the apical cell. At maturity the antheridial 

 branch resembles a miniature bulrush in shape, the anther- 

 idia-producing portion being involved in mucilage. In the 

 genus Corallina and its allies, the antheridia are produced 

 in conceptacles closely resembling those containing the 

 carpogonia, and possess the further peculiarity of having 

 the poUinoids furnished with one or two minute appendages ; 

 whereas in the other groups the pollinoids are spherical and 

 without appendages. 



Allusion has already been made to the occurrence of 

 fossil remains supposed to be algae in the older geological 



