16 



THE INDIVIDUAL ORGANISM 



from the main body of the cell. If one turns to unicellular organisms he 

 will find many sorts of regular and irregular shapes imposed by the sur- 

 rounding cuticles. In contrast to the great variety of size and shape shown 

 by a variety of kinds of cells, those of any one kind tend to be essentially 

 alike in both size and form. 











V 





Golgi bodies 



centrosome 



and 



centrioles 



nucleus 



cytoplasm 



cell 

 membrane 



mitochondria 



Fig. 2.1. Diagram of a generalized cell. 



Figure 2.1 is a somewhat diagrammatic drawing of a fairly typical 

 cell. The nucleus is shown as a sphere enclosed in a nuclear membrane, 

 turgid with a semifluid nuclear sap and containing an irregularly dis- 

 persed, somewhat more solid substance called chromatin. Chromatin 

 derives its name from the Latin chroma, "color," because of its marked 

 affinity for certain stains or dyes. The smaller sphere within the nucleus 

 is a nucleolus — another strongly staining body that is absent from some 

 cells and multiple in others. Just outside of the nucleus, and here shown 



