TWO EPIPHYTIC ALGAE 
JuLia W. SNow 
(WITH PLATE XVIII) 
Pirulus gemmata, nov. gen. 
This minute alga was first found in 1897 growing in a culture 
with other small algae in the botanical laboratory at the Univer- 
sity of Basel, Switzerland. Though the exact source of the cul- 
ture cannot be stated, it is known to have come from the vicinity 
of Basel. The alga was next found in a culture taken from some 
epiphytic mosses and liverworts from Guatemala presented to 
the writer by Miss F. G. Suir in January 1909. Though search 
has often been made for it in different parts of the United States, 
it has never been observed, and any record of its occurrence in the 
country has escaped notice by the writer. 
In its early vegetative state the alga shows nothing distinctive 
and might easily be taken for a small Chlorella or the germinating 
zoospore of some higher form (fig. 1), but in the shape of the adult 
cell and in its mode of reproduction it stands unique among all 
green algae. 
In shape the mature cell is pyriform, either perfectly symmet- - 
rical or somewhat irregular, 0.0084-0.0112 mm. in length and 
0.0056-0.007 mm. at its greatest breadth (figs. 2, 3). The color 
is a very light green. The parietal chloroplast is cup-shaped, with 
the large opening either at one side or at the smaller end of the 
cell, so that a portion of the cell is always colorless. A large vacuole 
is present (fig. 5a). No starch was found in either the material 
from Switzerland or in that from Guatemala. In the former no 
reaction for cellulose was obtained with the chloriodide of zinc, 
but in the latter a distinct reaction was shown with that reagent. 
A further difference between the two forms was noted in the num- 
ber of nuclei. In the Swiss material the mature cells when stained 
with hematoxylin showed four distinct nuclei, and in some instances 
eight were counted; while in the material from Guatemala a cell 
Botanical Gazette, vol. 51] [360 
