THE CARRIERS OF THE HERITAGE 15 



Robert Hooke, as early as 1665, had described 

 *' little boxes or cells distinguished from one another" 

 which he saw in thin slices of cork, and to him is 

 due the rather unfortunate use of the term "cell" 

 which has survived in biological writings to this day. 

 The reason this term is unfortunate is because walls, 

 which are ordinarily the characteristic feature of any 

 cell, such as a prison cell, are usually the least im- 

 portant part of the structure of a living cell, often 

 indeed being entirely absent. 



3. A Typical Cell 



A typical undifferentiated cell is represented 

 diagrammatically in Figure 3. Near the center of 

 the cell the nucleus is shown surrounded by a 



Cefl wall 



C«^to plasm 

 Centrosome 

 Nuclear membrane 



--Nucleus 

 .-Chromatin network 



Fig. 3. — Diagram of a typical cell. 



nuclear membrane. The nucleus, in common with 

 the enveloping cytoplasm, is made up of living 

 substance called protoplasm (Hugo von Mohl, 1846), 

 and around the whole there is usually formed a 



