THE CELL AS A MICKOBE 51 



small as to require 1,728,000,000 to make a cubic 

 inch. Others are many times smaller. Between 

 the extremes the variety in size is endless. 



Cells resemble microbes in form. They are 

 Spherical, Rod-shaped and Spiral. Under each of 

 these three general types the variation in form is 

 endless. Every part of every plant and every part 

 of every animal is built up with its own peculiar 

 kind of cell, and in each part the kind is varied 

 indefinitely to suit circumstances. 



The cell takes its food as does the microbe 

 absorbs it through its membranous coverings. It 

 digests in the same way, decomposing before ab- 

 sorbing its food. 



The cell grows and multiplies in the same way 

 as does the microbe. The two beings increase 

 alike in size until about twice their normal size, 

 then divide into two equal parts. These two new 

 beings increase and divide as before, and so on in- 

 definitely. 



As every microbe comes from a previous mi- 

 crobe, so every cell comes from a previous cell; 

 and, like the microbe, a single cell may multiply 

 itself into many millions in twenty-four hours. 



The cell enjoys locomotion in a similar way and 

 by similar means with the microbe. Some cells, 

 like some microbes, are stationary but have vibra- 

 tory motions. Other cells, like other microbes, 

 move freely about from place to place. The blood 

 cells, or corpuscles, circulate rapidly with the 

 blood through the whole system. And millions of 



