u 



Principles of PLant Culture. 



B 



microscope of moderately high power, is seen to be 

 made up of numerous little 

 sacks or cavities, more or less 

 clearly defined, called cells. 

 Cells from different beings, or 

 (Q^ C from different parts of the same 

 )Q0 being, may vary much in form 

 ^■I^'^-V ,S''°'«''°s four in- aji(j gi2e but they are seldom 



dividual plants o( a species ' •' 



pLnTb°eforconimenci7/to l^rge enough to be Seen with- 

 c "in! D*show"o^' tt?-ceus o^t magnifying power. Some 

 mgMy maSr'" '"^°*'- of the lowest plants and ani- 



Fig. 2. Part of a filament of a species of Spirogyra, a plant con- 

 sistin;; of a single row of cells united at their ends. The places where 

 the cells join are indicated by the yertical lines. Highly magnified. 



mals consist of single 

 cells (Fig. 1). Some of 

 the lower plants consist 

 of a single row of cells 

 united at the ends (Fig. 

 2) . The higher plants and 

 animals are made up of 

 many cells united, and 

 in these, the cells assume 

 different forms and prop- 

 erties in the different or- 

 gans (Fig, 3). In some 

 cases the united cells may 

 be readily separated from 

 one another, which shows each cell to be more or less 



s!=ilQS03 



Fig. 3. Showing cells of an ap- 

 ple leaf in a section from its up- 

 per to its lower surface. Highly 

 magnified. The spaces marked I 

 are cavities between the cells. 



