CHLOROPHYCEX 181 
However Cienkowski, one of the first to observe 
these “yellow cells” and to indicate their algal 
character, long ago based his argument on the 
observation that they continued to live and multiply 
long after the death of the animal; and Geddes, as 
well as Brandt, fully established their algal character 
by a series of minute observations made simul- 
taneously and independently. 
Reproduction is, as has been said, by the separation 
of vegetative cells. 
The Geographical Distribution of the order is world- 
wide. Zoochlorella has a wide distribution in the 
warmer seas, while Prasiola occurs in fresh-waters, 
as well as in the sea, throughout the world. Palmo- 
phyllwm is confined to Europe. Prasiola is the only 
genus recorded in British seas, though the order is 
represented by many genera in the fresh-waters of 
this country. 
PERIDINIE. 
General Characters.—Judged by our present know- 
ledge of this order, it occupies a position on the 
borderland between the plant and animal king- 
doms, while the balance of evidence certainly leans 
towards our regarding them as plants. Some of the 
forms, like Ceratiwm, are certainly plants. They 
occur in very varied forms, always free and never 
attached, except to each other in chains, as in Cera- 
tium Tripos, both in fresh-waters and the sea, and 
have, some of them, membranes, others not. They 
pass through a ciliated motile phase and a resting 
