Notes on Floridete. By George Massee. 567 



nences on the apical cell in Stypocaulon scoparium. Division of 

 the apical cell occurs in some highly differentiated genera as Cera- 

 mhim, Pandorea, and Dasya. Branches always originate directly 

 from axial cells, and even when the axis is polysiphonous and 

 densely corticated, their organic connection with axial cells can be 

 demonstrated. Sometimes, as in Dasya coccinea, adventitious 

 branches are present which originate from cortical cells. These 

 present the appearance of hairs and consist of a single row of cells. 

 When an apical cell is about to divide to form two branches, imme- 

 diately after a daughter-cell has been cut off, and while the apical 

 cell is still small, it is divided into two equal portions by the appear- 

 ance of a septum in the direction of the axis of growth of the 

 branch. If the branches are all developed in one plane, this septum 

 is at right angles to the plane of the branches ; but when they are 

 arranged in a spiral, the septum is at right angles to the plane of 

 the branch immediately below. After the formation of the vertical 

 septum in the apical cell, the two daughter-cells commence growth, 

 but there is no connection between the origin of branches and their 

 ultimate arrangement. If the two cells develope at the same rate, 

 and diverge at equal angles from the direction of the podium from 

 w r hich they originate, a dichotomy is the result, as may be seen in 

 Pandorea traversii, and sometimes in Dasya coccinea. If one cell 

 grows more vigorously than the other, and in the same direction as 

 the podium, the other growing at an angle, and resembling a lateral 

 branch, a sympodial arrangement results, as is usual in Dasya 

 coccinea. When branches originate as lateral protuberances the 

 ultimate arrangement may be dichotomous, as in Callithamnion 

 corymbosum ; sympodial, in C. tetragonum ; or monopodial in 

 C. polyspermum, depending on the relative development and direc- 

 tion taken by the branch and the axis from which it springs. In 

 the filamentous members of the Floridese, in which the axial cells 

 remain, " protoplasmic continuity," which is so conspicuously 

 developed in the group, enables an observer to dstermine with 

 certainty the mode of origin of any branch, even when fully 

 developed, depending on the number and arrangement of the threads 

 of protoplasm connecting the protoplasts of adjoining cells. When 

 the branch originates as a lateral protuberance, the curved septum 

 that cuts it off' from the parent cell is pierced by one protoplasmic 

 thread, which connects the protoplasm of the one-celled branch 

 with that of its mother-cell. This one -celled branch is an apical 

 cell, from which in due course is cut off a segment. This seg- 

 ment constitutes the basal cell of the new branch, and is never 

 connected by protoplasmic threads with more than two cells, the 

 one from which it was segmented below, and the one cut off from 

 it above. When branches originate from the division of an apical 

 cell, the two sister cells resulting from the formation of a vertical 



