26 PHARMACEUTICAL BOTANY 
Observe the Amoeba as it moves and find out whether the 
direction of movement is in one line or several. 
Note that Amoeba moves by extending protoplasmic processes 
called pseudopodia, (false feet). At a particular point the ecto- 
plasm is pushed out in the form of a small pimple-like elevation; 
This increases in size, still consisting of ectoplasm only until, at 
last, granules from the endoplasm stream into it and the projec- 
tion or pseudopod comes to possess the same structure as the rest 
of the Amceba. This method of movement is called ameboid 
movement. ‘The same kind of protoplasmic movement is shown by 
the slime molds and white blood corpuscles. 
Note that when the organism comes in contact with a diatom 
or any other particle of food pseudopodia are extruded and the 
food is enveloped, so sinking into the cytoplasm. The food is 
taken in with a small amount of water, which forms a surround- 
ing bubble or food vacuole. This constitutes the first step in the 
process of nutrition and is called ingestion. If watched sufficiently 
long, the protoplasm of the diatom or substance of the food 
particle ingested is slowly dissolved or digested through the 
agency of some enzyme or enzymes within the endoplasm. As 
it moves on, the Amoeba ejects or expels the cell wall of the 
diatom or any other insoluble substance. 
An enzyme is a substance of biologic origin which has the 
property of causing a change in its surrounding medium without 
becoming involved itself. Through enzyme action the pre- 
viously water insoluble (colloidal) protoplasm or food of the 
Amceba is broken down into water-soluble (crystalloidal) 
substances which are capable of diffusion. The process whereby 
water-insoluble foodstuffs are made water-soluble through 
enzymic action is called digestion. 
Mineral mattefs are taken in by the Amceba with its food in 
the form of a weak, watery solution. The next step is for the 
organism to rearrange the elements of digested food, mineral 
salts and water in such a way as to form new particles of living 
protoplasm. These are deposited among the pre-existing par- 
ticles and so assimilated or converted into the living substance of 
the Amoeba. One effect of this formation of new protoplasm is 
growth. This process of growth by the interposition of new 
