854 LIFE : OUTLINES OF GENERAL BIOLOGY 



tiated. We have been accustomed to extend the long familiar cell- 

 theory, as the most fundamental and verifiable generalisation about 

 the form of organic beings which we possess, to this bacterial world 

 as well. But is this really sound, or safe ? Not without modifying our 

 ordinary and well-established conception of the cell, of which so 

 much is known, despite its protean forms, changes and manifesta- 

 tions. In all ordinary cells we find also a nucleus, with broadly 

 similar structure and behaviour, and these peculiarlj^ characteristic, 

 despite all minor differences, in cell-division ; witness its predominant 

 form, of complex mitosis. True, this complex division process is 

 not invariable; direct division (amitosis) is also well-known; but 

 after all only in special cases, and not as invariably characteristic of 

 any metazoon or metaphyte, as a whole. At a time when the nucleus 

 had not been made out in certain very simple Protozoa, Haeckel 

 separated them from all other life-forms, as "Monera", and in 

 distinction from all nucleus-possessing cell forms, as Endoplastica. 

 In a number of these the nuclei were subsequently found, and so 

 this distinction was dropped; yet exceptions still remain. Still 

 these little affect the general importance of the presence or absence 

 of the nucleus which we are emphasising here; save possibly to 

 suggest some early phase of cell-evolution. 



In the bacterial underworld multiplication by division has alwa3^s 

 been familiar, indeed at the most astonishing rates; yet here our 

 high-power lenses and skilled eyes behind them, with application 

 of every known microtechnique as well, have alike failed to confirm 

 the (sometimes alleged) presence of any structure that can safely 

 be identified as a true nucleus, with mitotic division behaviour, or 

 even with amitotic; but at most only minute, and more or less 

 indefinitely situated granulations. These can, indeed, be stained like 

 nuclei, but they appear in mature forms rather than in the newest 

 and youngest, whereas, were they true cells, it is there we should 

 expect most clearly to make them out. Nucleo-protein substances are 

 indeed found by the biochemist ; but that is not to be wondered at, 

 since bacteria partake of general protoplasmic nature. In aU these 

 ways, then, are we not being driven towards the conclusion that 

 bacteria, albeit resembling cells in their multiplication by division, 

 are yet of deeply inferior order to the cells proper of our ordinary 

 biological experience? And if so, can we shrink from recognising 

 bacterial life as a lower world altogether, deeply and remotely 

 inferior to that of cell-life proper? In fact, may we not have to 

 constitute a veritable Sub-Kingdom, lower by far than Protozoa 

 and Protophytes? And since these, as truly cellular, are one with 

 Metazoa and Metaphytes, shall we not have to call all these Celhdares 

 (or some such name) and so relegate the bacterial world to a lower 

 sub-kingdom altogether, described, say, as Pre-Cellulares ? 



Filter-Passers. — Leaving now Bacteria as we see and know 



