THE BUILDING-STONES OF THE ORGANIC WORLD 69 



Each cell we must conceive to be a minute chemical laboratory 

 within the narrow space of which there goes on the sum total of 

 all the processes, changes, and movements which we are wont to 

 designate as life. Whenever and wherever on earth we may find 

 life, we shall always find it bound to a cell, that is, to an ele- 

 mentary organism, the body of which consists of two different 

 substances or parts, the protoplasm and the nucleus. 



Until recently numerous investigators maintained the exist- 

 ence of more primitive organisms, so-called Monera or Cytodes, 

 which had not yet attained the organization of the cell. But 

 since Haeckel established his class of the Monera, the number of 

 those elementary organisms which were said to be without a 

 nucleus has decreased year by year in proportion as our optical 

 instruments and staining methods have become more perfect. It 

 is not difficult with modern instruments to demonstrate a typical 

 nucleus-cell in many cells which were formally believed to be 

 without a nucleus, for instance, various species of amoebae, myxo- 

 mycetes, &c. It is not necessary for the nucleus to be formed 

 homogeneously; in many cases, for instance in the protozoon 

 Pelomyxa pallida, the nuclear substance is distributed in 

 numberless minute granules throughout the entire protoplasm. 

 Of other cells which at the mature stage are without a nucleus 

 in particular, the red blood-corpuscles of mammals we know 

 that they have originated from nucleated cells. 



The only remaining non-nucleated cells, therefore, are the 

 bacteria and the yeasts, but evidence is accumulating tending to 

 show that even these are typical nucleated cells. Quite recently 

 Wagner succeeded in demonstrating not only that yeast-cells 

 have a nucleus, but also that they are cells with a highly 

 organized nuclear apparatus. According to the investigations 

 made by Biitschli it seems further probable that the bacteria, 

 too, are differentiated into plasm and nucleus. This excellent 

 investigator found that in some of the larger bacteria spirilla, 

 spirochaetse, &c. it is possible with a high-power microscope 

 and the aid of special nuclear dyes to demonstrate the presence 

 in the body of the bacterium of two different substances, one of 

 which represents the protoplasm, the other probably a primi- 

 tive nucleus. All but those that are bound by prejudice must 

 therefore admit that science knows not a single non-nucleated 



