ORGANISED AND UNORGANISED SUBSTANCES. 



13 



nourishment and excretion, its growth, movement, change of form, 

 and reproduction. With participation of the nucleus it begets by 

 division or endogenous cell formation new units like itself, and 

 furnishes the material for the construction of tissues, for the for- 

 mation, growth and change of the body. With justice, therefore, is 

 the cell recognised as the special embodiment of life, and life as the 

 activity of the cell. 



FIG 2. Amoeba (Protogenes) porrecta (after Mas Schultze)1 



Nor is this conception of the significance of the cell as the criterion 

 of organisation and as the simplest form of life contradicted by 

 the facts that the nucleus also sometimes fails (so-called cytodes of 

 Hseckel), and that bodies undoubtedly manifesting vital phenomena 

 are known which are structureless under the highest power of the 

 microscope. Many Schizomycetes (Micrococcus) are so small that 

 it is difficult to distinguish them in some cases from the granules 

 of precipitates, especially when they show only molecular motion 

 [Brownean movements] (fig. 3). Consequently, the living protoplasm^ 

 with its unknown molecular arrangement, is the only absolute test of 

 the cell and organism in general. 



While appreciating the essential differences which have been 



