The Cellular Structure of Plants 



17 



Fig. 6. Plant cells : A is from a moss leaf ; B is from a squash-vine 

 hair ; C is a starch-filled cell from a potato tuber ; and Z> is a cell from 

 the palisade layer of a leaf. E shows a cell in cross-section. 



that can liberate energy from a part of its food and with the 

 remainder construct more matter Like itself, and that regulates 

 its own activities. It is self-constructing and self-regulating, 

 the only truly automatic mechanism known. 



Differentiation of the protoplasm. The living matter of the 

 cell is primarily differentiated into two parts, the cytoplasm and 

 the nucleus. The cytoplasm constitutes the bulk of the proto- 

 plasm and forms a definite layer within the cell wall and surround- 

 ing the central vacuole. 



