Smith—The Organization of the Colony. 
1201 
ence in the variation of the cleavage of the mother cell on the 
position of the cells in the coenobe. When the autospores are 
motile (Pediastrum) there is little influence in the manner of 
cleavage of the mother cell on the arrangement of the cells in 
the colony, but the variations in the cellular arrangement are 
largely biaiometamorphic. 
The fact that these variations are not uniformly present in 
all of the colonies of a culture shows that a distinction should 
be made between variations in the external environment and 
changes in internal conditions of the cell. Possibly it would 
be better to distinguish between internal and external biaio- 
metamorphosis. External conditions can be varied but the 
internal conditions cannot be controlled and when variations 
are laid to changes in internal conditions we are using a phrase 
which gives us absolutely no concept of the actual processes in¬ 
volved. 
Since we have this great divergence in different coenobia 
that are all descendants of a single cell and which, at least in a 
liquid medium, have been kept under the same conditions of 
temperature, light, and chemical environment we must say that 
a greater importance, must be attached to internal that external 
conditions. The internal conditions in the cell are constantly 
changing and as a result the four cells formed from a single 
mother cell are not alike in internal condition and the colonies 
formed are not wholly alike. It is this constant change in the 
cell that is the main cause for whatever variation occurs in the 
process of reproduction. 
Summary. 
The arrangement of the cells in coenobic algae may be classi¬ 
fied conveniently according to the relationships of the cell axes. 
Pure cultures or uni algal cultures should be used for study¬ 
ing the variations occurring in any given species. 
The marked variation described by Grintzesco for Scene - 
desmus acutus was not found in my pure cultures. 
Changes in the environment produce changes in the indi¬ 
vidual cells of the coenobe (Biaiometamorphosis), but have 
small effect upon the special interrelationships of the cells. 
