U N 1 T 1 r: S OF LIFE 



Forty years ago (1S64) I tried in vain to detect a 

 nucleus in the naked, living, mobile protoplasm of a 

 few small rhizopod-like protists (protamocba and proto- 

 genes). Other observers, who afterwards studied simi- 

 lar unnucleated cells (Gruber, Cienkowski, and others), 

 were no more successful. On the ground of these ob- 

 servations, which were often repeated afterwards, I 

 formed the class of the ni oncr a — the simplest unnucleated 

 organjsms — in my General Morphology in 1866, and 

 pointed out their great importance in solving some of 

 the chief problems of biology. This importance has 

 been much enhanced of late, since the chromacea and 

 bacteria have also been recognized as unnucleated cells. 

 Biitschli has, it is true, raised the objection that their 

 homogeneous plasma-body behaves, not as cytoplasm, 

 but as caryoplasm (or nuclein), and so that these sim- 

 plest plastids correspond, not to the cell-body, but to 

 the nucleus of other cells. On this view the bacteria 

 and chromacea are not cells without nuclei, but nuclei 

 without cell-bodies. This idea agrees with my own in 

 conceiving the plasma-body of the monera (apart from 

 its molecular structure) as homogeneous and not yet ad- 

 vanced as far as the characteristic differentiation of in- 

 ner nucleus and outer cell-body. Bearing in mind that 

 these essential parts of the cell (in the view of most 

 cytologists) are chemically related yet different from 

 each other, we have three possible cases of the original 

 formation of the nucleated cell from the unnucleated 

 cytode: (i) The nucleus and cell-body have arisen by 

 dififerentiation of a homogeneous plasm (monera); (2) 

 the cell-body is a secondary growth from the primary 

 nucleus; (3) the nucleus is a secondary development 

 from the cell-body. 



On the first view, which I hold, the plaspa. or living 

 matter, of the earliest organisms on the earth (which 

 can only be conceived as archigonous monera) was a 



157 



