28 WHAT IS LIFE ? 



flattened or disk-like, and we call them blood corpuscles 

 it is these which give the colour to the blood ; some- 

 times as minute fibres, and sometimes like a central 

 ball throwing out fibres in all directions, their elon- 

 gating fibres meeting each other, forming a perfect 

 network like felt, of great complexity, and we have some 

 of the factors in the structure of nerves nerve-cells. 

 All, however, have one fundamental characteristic, 

 they are alive. And it is their life in the aggregate 

 which forms that complex condition which we call 

 human life. 



But there is another peculiarity. Each cell has in- 

 side its body a more or less spherical object called the 

 " nucleus" and between this object and the wall of 

 the cell is a more or less plastic material. And 

 besides this minor object, there is sometimes to be seen 

 another object inside the nucleus called a " nucleolus" 

 It is important that we keep this object in mind. 



FIG. 4. A typical nerve-cell from the spinal cord, n nucleus ; n' nucleolus ; 

 p branched processes, the fine edges are cut away ; np unbranched 

 process, which connects with a nerve. (From Huxley's " Lessons in 

 Elementary Physiology," 1893, p. 360.) 



These cells often secrete fluid, and this fluid often 

 becomes solid, more akin to what is called inorganic 

 material. So that an organism, a living creature, is 



