20 EASY LESSONS IN VEGETABLE BIOLOGY. 



the white blood-cells, described in Sec. 2, Chap. II, 

 wander out of the blood-vessels in order to construct 

 the various parts of the body as they may be needed. 

 (Fig. 2.) 



3. Another peculiarity of living matter is the 

 power of nutrition and growth. The non-living in- 

 creases in size by external additions, but bioplasm 

 selects appropriate material from its food, (or pabu- 

 lum,) changes the chemical relations of this material, 



Fig. 2. 



and appropriates it to its own structure in such a way 

 that it grows from within. It is altogether different 

 from the enlargement of a crystal, or of the increase 

 of any thing without life. 



4. Bioplasm can generate or reproduce its own 

 kind of living matter. No living being exists which 

 did not originate from living matter of a similar 

 kind. Some persons have thought that they have 

 seen the beginning of life in some forms of simple 

 beings, originating by what has been called sponta- 



