THE NUCLEUS 99 



differentiated into two parts, a nucleus, in the morphological sense, 

 distinct from the cytoplasm does not represent the primary and 

 universal form of the living organism or unit, but is to be con- 

 sidered as a stage in the evolution of living beings, a stage which 

 many living beings have not reached. Thus a bacterial type of 

 organism, in which the chromatin is scattered through the proto- 

 plasmic body in the form of chromidial granules, and which there- 

 fore does not possess a true nucleus, is not to be regarded as a cell, 

 but as representing a condition antecedent to the evolution of 

 the true cellular type of structure. In all Protozoa, on the other 

 hand, the entire plan of the organization is founded on the type of 

 the cell, which is to be regarded as the starting-point in the evolu- 

 tion of the entire animal and vegetable kingdoms (compare Min- 

 chin, 75). This point will be discussed further in a. subsequent 

 chapter (p. 464). 



Bibliography. For references see p. 477. 



