THE EVOLUTION OF THE MIND. 259 
United States. Its adjustments, checks, and balances 
are more perfect. It should in its changing relations be 
compared rather with the great unwritten constitution 
of civilized society. The laws of society spring from 
the laws governing the development of the single cell. 
If we knew the latter “all in all,” as Tennyson says — 
of the flower, “we should know what God is and 
man is.” 
If we could follow any life problem to its uttermost 
detail, we should have the clew to all life. 
Among the protozoa, as already stated, all activities 
are centred in the single cell which forms the animal 
unit. Each cell is sufficient unto itself. 
It is independent and free, but it is at 
the same time unspecialized and in- 
effective. Its career offers no wide play for volition, 
for a single life unit can not control the elements which 
surround it. It is the sport of the wind and the wave. 
But the recognition of self and non-self, which in one 
form or another is the attribute of all life, is not want- 
ing among the protozoa. Some of them develop this 
sense to a large degree. It is said that among the 
rhizopods are those whose appendages or pseudopodia 
are at once cast off if they come in contact with the ap- 
pendages of another of the same species. This recog- 
nition of self and non-self is not intellect, but it is 
homologous with the impulses on which in the higher 
types personality depends. 
All sensation has reference to action. If a creature 
is not to act it can not feel. Wherever motion exists 
there is some sensitiveness to external 
conditions, and this is of the nature of 
mind. In a compound organism the na- 
ture and position of the sensorium or mind centre de- 
pends on what it has to do, or rather on what were the 
Activities of 
protozoa. 
Sensation re- 
lated to action. 
