Cells and Tissues 



6 9 



4. As to fusion 



(a) Without protoplasmic contents and with markings 



Vessels, end fusion complete, found in wood, 

 conveying transpiration current and air. 



(b] With protoplasmic contents without markings 



Sieve tubes, ends perforated, found in phloem, 



carrying elaborated food. 



Latex vessels, end fusion complete, forming a 

 network, found in various parts, carrying latex. 

 All of the cells mentioned here except latex tubes may be 

 found in the oak stem (Fig. 72). 



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FIG. 70. Cell structure. A, young parenchymatous cells ; />, protoplasm ; 

 k, nucleus ; kk, nucleolus ; B, older cells showing vacuoles ; s in C, the vacuoles 

 have become larger ; y, the protoplasm has withdrawn from the wall and the 

 cell will become inactive. 



5. As to contents 

 A typical cell has 



(a) Protoplasm consisting of cytoplasm 



with outer layer, ectoplasm. 

 inner layer, endoplasm. 

 nuclear membrane, kinoplasm. 



(b] Nucleus, with nucleolus. 



