46 PLANT LIFE 
remain in this condition for about four days 
the strong salt solution is gradually replaced 
by sea-water. The ellipsoidal cells swell out 
until they approximately fill the space they 
previously occupied within the old membrane. 
But the disunion has obliterated the mutual 
relationship formerly existing between cell 
and cell. Each one proceeds to develop with- 
out any reference to the rest, and puts out a 
basal attaching organ below, which usually 
penetrates the adjacent cell cavity. Later 
on the cell also proceeds to grow in the 
apical direction. Thus the individual cells 
of the filamentous colony have been, in this 
experiment, released from the influence which 
bound them together into an organism, and 
have recovered complete autonomy and in- 
dividuality. This has occurred as the result 
of sundering the protoplasts from all com- 
munication with one another for the period 
of time during which they remained con- 
tracted in the strong salt solution. 
An experiment such as this is specially 
valuable, since it enables us to appreciate 
not only the reality of the continuous inter- 
change of material between cells that are 
in close contact, whereby co-ordination is 
rendered possible, but it serves to show how 
closely this co-ordination to form an organism 
is bound up with such mutual interchange. 
For the protoplasts, although separated by 
membranous cell walls from each other, 
are yet in intimate connection; in many 
