DEVELOPMENT OF SPORANGIA IN RHODOCHORTON. 203 
(tetraspores) are thus quadrants, not tetrahedra as, for example, 
in the genus Polysiphonia. The apical cell meantime increases 
in length and subdivides transversely into a new apical cell and a 
basal cell, from which latter a new sporangium arises in like 
manner. When the spores are mature the wall of the sporangium 
ruptures at the apex and the spores escape, the empty spor- 
angium remaining attached. The parent cell then gives off 
another bud into the cavity of the empty sporangium (fig. 10). 
Usually, though not invariably, the second bud, after separation 
from the parent cell, divides transversely into an apical cell and 
a basal cell from which a new sporangium arises, the basal cell 
being sheathed by the torn wall of the first formed sporangium 
(fig. 10). Often, however, the second bud itself becomes the 
mother cell of a sporangium, and in such cases a series of 
sporangia may be so formed, the torn walls of preceding sporangia 
remaining as sheaths round the base of the sporangium of the 
time being (fig. 7). Other conditions still are to be met with. 
The bud may divide into a basal and apical cell, the sporangium 
being developed not from the basal cell but from the apical cell 
directly (fig. 6). 
The spores when shed germinate into cell-rows sparingly 
branched. The sporangia begin to be formed from January 
onwards, so that by the end of March eem filament bears at its 
apex a cluster of sporangia. 
The method of innovation deseribed as occurring in the 
development of the sporangia is only an extension of the mode of 
renewed growth of the vegetative filaments. Injury toa filament 
and removal of the apex is followed by apical growth of the next 
uninjured cell into the cavity of the ruptured cell (figs. 8, 9) 
The sporangia of R. floridulum, Näg., show similar inno- 
vations to those described as occurring in R. Rothii (fig. 12). I 
have not met with R. chantransioides, Reinke, and am therefore 
unable to say whether the same phenomenon is exhibited by that 
species. Certainly Reinke’s figures * do not indicate any basal 
sheaths such as I have described as occurring in R. Rothii and 
R. floridulum. I may add that these sheaths may also be observed 
in R. membranaceum, Maq. 
Similar phenomena in the development of sporangia are known 
to occur in the Sphacelariaceæ and other groups. 
* Atlas deutscher Meeresalgen, tab. 21. 
R2 
