Locomotion by Pseudopodia

A.  Some attributes of pseudopodial locomotion
	1.  Basic hypotheses
		a.  Push mechanism
		b.  Pull mechanism
		c.  Combination
	2.  Organism structure
		a.  Material in body is a colloid
		b.  Colloids are special kinds of solutions--particles 
			that are dispersed in the medium are large, 
			typically in living system proteins in a water
			matrix.
		c.  Colloids can occur in a variety of states; solid
			liquid or gas.  Protoplasm can occur as either
			a solid or a liquid.  An example of a gaseous
			colloid is fog.
		d.  Colloids are very pH, temperature and pressure
			sensitive.  Changes of state may occur through
			very slight pH changes.
		e.  A sarcodine has two physiological areas, a plasma
			sol and a plasma gel.  These areas correspond
			to different colloidal states.
		f.  A sarcodine has two structural areas, an ectoplasm
			and an endoplasm.  These areas are somewhat
			correlated to the physiological areas, although
			not exactly
		g.  Sarcodines may have at least three different kinds of
			pseudopodia
			1.  lobopodia-blunt pseudopods, such as seen in 
				amoebae
			2.  actinopodia--pointed pseudopods, often with 
				axial support, such as seen in many
				radiolaria
			3.  reticulopodia--meshwork of pseudopods as seen
				in foraminifera.
	3.  Mechanism of motion
		a.  Push-the force is produced at the back of the cell
		b.  Pull--the force is produced at the front of the 
			cell
		c.  A variety of evidence has been used to support both
			contentions.
		d.  Work by Robert Allen indicates though that it for many
			protists, it might be a pull
			1.  Allen was studying a sarcodine in a capillary
				tube.  He crashed the objective lens into
				the tube, thus breaking the creature into
				two.  Front half continued to move forward.
				Thus Allen, belives that it couldn't be a
				push force.
		e.  What may be taking place is a change in the structure
			of the proteins in the cytoplasm.  With proteins
			folding and unfolding to produce sol or gel state.
		f.  ATP-ase stop all activity.
		g.  Surveys show that actin and myosin are present
B.  Relationships between the sarcodines and flagellates
	1.  Two groups are in the same phylum
	2.  Flagellates often show at different stages in the their life
		cycles, the ability to move by pseudopodial action.
	3.  Ciliates are less closely related and don't show pseudopodial
		activity.
C.  Protists are not the only creatures to use pseudopodial activity.
	1.  Many cells in both the verts and inverts. use pseudopodia, eg.
		white blood cells, wandering amoebocytes in sponges, etc.