40 SYMBIONTICISM AND THE ORIGIN OF SPECIES 



tozoan microorganisms and the bacteria, led Haeckel to 

 propose the term "protista" to include a lowest order of 

 living organisms, a distinct kingdom of living things. In 

 this connection too, the suggestion has been made that the 

 ''bacteria" are the primordial organisms from which all 

 higher forms of life have sprung. (So far as I know, no 

 one has ever attempted to expound a concrete theory of the 

 nature of this early evolution. The evidence which will be 

 presented in a later chapter of this book, estabhshes a basis 

 for a better understanding of the nature of such an evolu- 

 tionary process.) 



The second factor that complicates the question of the 

 evidence or basis for calhng mitochondria bacteria, con- 

 cerns our knowledge of protoplasm and particularly cyto- 

 plasm. The nucleus has long been looked upon as the con- 

 trolhng factor in the cell. The center of vital activity is 

 supposedly located in the nuclear portion. Bits of cyto- 

 plasm removed from the cell do not continue to grow and 

 function as an independent entity. The remarkable anal- 

 yses of chromosomes in relation to heredity, that have re- 

 cently been made by students of genetics would appear to 

 exclude any possible independent participation of cyto- 

 plasmic bodies. On the other hand, Conkhn and Wilson 

 beheve that the cytoplasm participates in hereditary trans- 

 mission. It might be argued that parts of the cytoplasm 

 should be capable of independent existence. Such argu- 

 ments might proceed along various lines. It might be 

 assumed that the cytoplasm as such (not the formed bodies 

 that it contains) may have such properties of self perpetu- 

 ation. Or it might be assumed that formed bodies of 

 the cell having these properties are a part of the cytoplasm. 

 This raises a subtle question which must be left for the 

 future to determine. Mitochondria, apparently, represent 

 the end result of the development of an absolute micro- 

 symbiosis. What is the nature of the intimate relationship 



