Natural History of the Animalcules. 109 
of the first, so that the liquid substance passes not into 
one protrusion only, but into the several others. By 
this flowing on of the body substance into the various 
protrusions, the shape of the organism is constantly 
altering ; and the motion of the whole is determined by 
the direction in which the protrusions take place — a 
dire6tion that is constantly changing, to so great an 
extent as to give the observer the impression that the 
little organism has not the faintest idea of what it wants 
to do, vacillating continually as to the direftion in which 
to move, and after having made a start, changing about, 
here, there and everywhere, in a manner that is quite 
entertaining, though, to say the least of it, perfeftly 
hap-hazard. Doubtless the Animalcule has a perfe6lly 
different explanation to offer of its own case, and if it 
were capable of observing the movements of the lords of 
creation, w T ould be able, from its vantage-ground of per- 
feft mobility, to ascribe a very farcical aspeft to the 
locomotion of a jointed body. 
In another species, in which the protoplasm is denser, 
the protrusions have more definite form. When retraced, 
however, they are entirely absorbed into the general 
substance, and leave not a trace of their former existence. 
These temporary protrusions are known technically as 
pseudopodia (or false-feet) ; and it is owing to the con- 
stantly changing form which they occasion, that the 
organism has received the common name of Proteus-ani- 
malcule, and the scientific one of Amoeba — i.e. changing. 
Still gazing closely at the little obje6l, we notice that 
as it creeps or flows slowly on its way, it comes in con- 
taft with various particles, organic and inorganic. A 
certain sele6live power is manifested in its treatment of 
