14 



Principles of Plant Culture. 



B 



of numerous little sacks or cav- 

 ities, more or less clearly defined, 

 called cells. Cells from different 

 beings, or from different parts 

 of the same being, may vary 

 much in form and size, but they 

 are seldom large enough to be 



FIG. 1. Showing four indi- 

 vidual plants of a species of seen without magnifying power. 



Protocols. A shows a plant Some f th j t 1{mt d 



before commencing to divide 



into other plants. B, c and D animals consist of single cells 



show how the cells divide to (pj 1) g f ^ } 



form other plants. Highly v 



magnified. plants consist of a single row of 



cells united at the ends (Fig. 2). The higher plants 



Ii : AfoAfc 



'JW 



FIG. 2. Part of a filament of a species of Spirogyra, a plant consisting 

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

 join are indicated by the vertical lines. Highly magnified. 



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 an independent struct- 

 ure. As a rule, each cell FlG 3 Showingcellsof the apple leaf 



is Surrounded by its OW11 in a section from its upper to its lower 



surface. Highly magnified. The spaces 

 Closed Cell- Wall. marked I are cavities between the cells. 



