98 The Botanical Gazette. [March, 
The motion of the motile cells through the water is quick 
and sometimes they dart to one side in a manner that sug- 
gests at once the motion of certain infusoria. They come to 
rest slowly, moving occasionally from side to side some time 
after they seem to have settled down. While they sometimes 
spin around on the ciliated end just before they settle down, 
they do not attach themselves in a perpendicular position but 
rest on one side. The length of time these cells remain in 
the motile condition, and the character of their movements, | 
forms a striking contrast to the motile phases of other alga, 
such as Cladophora, Draparnaldia, Ulva, etc., whose 200 
spores settle down within a few hours to develop a new itt 
dividual. 
Non-motile stage. 
The motile cells when they came to rest in a Van Tieghem 
cell, did not divide for two or three days and after that only 
at intervals of two or three days. The division consists of a 
longitudinal splitting of the cell into a pair of similar cells 
and hence in the colonies they tend to show a pretty fy 
ular arrangement in groups of twos and fours. They are about 
the same size as the motile cells but inclined to be a littl 
shorter and somewhat broader in their proportions. That 
there is a common gelatinous envelope surrounding young 
colonies is often clearly shown by the quantities of bacter 
that swarm at a fixed distance from the cells (plate 4 fg. 
2). This gelatinous envelope is not a marked character how 
ever and in large colonies it is quite insignificant (plate Xs 
fig. 3), although it is not difficult to prove its existence with 
proper stains. | 
ot al 
The chromatophores, in the non-motile cells, are ! I 
ranged in any regular manner and sometimes the entire Ge 
appears of an almost uniform blue-green tint. The chr 
ophores vary in size but are usually discoid in shape ae 
| 
XI, fig. 4). They may be brought out with great , 
ness in cells after treatment with absolute alcohol, and app" 
perfectly homogeneous. be 
One or two, and rarely three, pigment spots ar pai 
found near the middle of the cells on the periphery: i. 
color however is not so bright as in the motile stage but i 
clined to be a brownish-red. dea 
A well defined nucleus (plate XI, fig. 5) can easily be art 
onstrated when specimens, well fixed and hardened, : 
