ORIGIN OF THE METAZOA 



49 



Willmer (1956) in discussing the change of form of Naegleria 

 points out that the rhizopod can be in any one of three phases: 



(1) in the flagellate stage with a definite polarity; 



(2) in the amoeboid phase with pseudopodia coming from all 

 over the body ; 



(3) aggregated in the form of a sheet of tissues. 



It would seem that this protozoan has no difficulty in losing its 

 polarity and therefore that the difficulties raised by Baker con- 

 cerning the changes from Protozoa to Metazoa are not as great 

 as he suggests. 



What conclusion then can be drawn concerning the possible 

 relationship between the Protozoa and the Metazoa? The only 

 thing that is certain is that at present we do not know this relation- 

 ship. Almost every possible (as well as many impossible) relation- 

 ship has been suggested, but the information available to us is 

 insufficient to allow us to come to any scientific conclusion regard- 

 ing the relationship. We can, if we like, believe that one or other 

 of the various theories is the more correct but we have no real 

 evidence. 



