92 THE ORIGIN AND EVOLUTION OF LIFE 



have neither nucleus nor chromatin; others admit the presence 

 of chromatin, but deny the existence of a formal nucleus; others 

 contend that the entire bacterial cell has a chromatin content; 

 while still others claim the presence of a distinctly differenti- 

 ated nucleus containing chromatin. Most of them, however, 

 are agreed as to the presence in bacteria of granules of a chro- 

 matin nature, while they leave as an open question the pres- 

 ence or absence of a structurally distinct nucleus. This con- 

 servative point of view is borne out by the fact that all the 

 common bacteria have been found to contain nude in, the spe- 

 cific nuclear protein complex. Nuclei and chromatin were 

 ascribed to the Cyanophyce^, by KohP as early as 1903 and 

 by Phillips'- and by Olive^ in 1904. 



It is also a matter of controversy among bacteriologists 

 whether protoplasm or chromatin is the more ancient. Cell 

 observers (Boveri, Wilson, Minchin), however, are thoroughly 

 agreed on this point. Thus Minchin is unable to accept any 

 theory of the evolution of the earliest forms of living beings 

 which assumes the existence of forms of life composed entirely 

 of protoplasm without chromatin.' All the results of modern 

 investigations — the combined results, that is to say, of cytology 

 and protistology — appear to him to indicate that the chroma- 

 tin elements represent the primary and original living units or 

 individuals, and that the protoplasm represents a secondary 

 product. As to whether chromatin or protoplasm is the more 

 ancient, Boveri suggests that true cells arose through sym- 

 biosis between protoplasm and chromatin, and that the chro- 

 matin elements were primitively independent, living symbioti- 

 cally with protoplasm. The more probable view is that of 

 Wilson, that chromatin and protoplasm are coexistent in cells 



iKohl, F. G., 1903. = Phillips, O. P., 1904. = Olive, E. W., 1904. 



* Minchin, E. A., 1916, p. 32. 



