1911] SNOW—EPIPHYTIC ALGAE 361 
showed but a single nucleus (fig. 5). In all other respects, how- 
ever, in the shape and the size of the cells, the nature of the 
chloroplasts, and mode of reproduction, but slight variations in 
the two forms occurred. The different results obtained in the 
membrane tests might possibly be explained by a difference in the 
reagents used, in which case the only real difference would lie in 
the number of the nuclei. As this is an internal difference rather 
than an external one, the two algae have been regarded as forms of 
the same species. 
The most distinctive characteristic of this alga is its reproduc- 
tion. Whereas all other similar forms multiply either by fission 
or internal division, producing either zoospores or non-motile 
gonidia, this form reproduces by budding. The smaller end of 
the pear-shaped cell elongates, then a slight constriction occurs 
near the end, and a membrane is put across, forming a cell which 
is nearly spherical, with a diameter much smaller than the original 
cell (figs. 3, 4). This new cell does not become detached imme- 
diately, but again the smaller end of the parent cell elongates and 
a second cell is produced between the original cell and the one last 
formed. This is repeated continuously, and often a chain of 
12-14 cells is produced before the cells separate, the oldest of the 
series being farthest away from the original cell (fig. 6). Growth 
usually begins in each new cell as soon as formed, so that there 
is a slight increase in size from the youngest to the oldest of the 
chain, and often the largest ones of these begin to reproduce them- 
selves before the breaking up of the filament takes place (figs. 7, 8). 
Instances were observed where new cells were seen to originate 
from opposite ends of the parent cell, but this was a rare occurrence. 
The alga was cultivated in pure cultures under various condi- 
tions and in various concentrations of Knop’s solution, but was 
found to vary little except in rapidity of growth and length of 
filament or chain formed. The greatest increase in the amount 
of material occurred in 0. 2-0. 5 per cent Knop’s solution and on 
agar-agar plus o.2 per cent of the same solution; while the longest 
chains of cells occurred in the weaker concentrations, such as 0.05 
and 0.1 per cent, and on agar with a 0.2 per cent solution. With 
an increase in concentration there was a regular decrease in the 
