238 



General Biology 



Fig. 139. Conducting Tissues. 



A. Collateral type, Bamboo stem. 1. Fibrous tissue. 2. Ducts. 3. Sieve. 



B. Collateral Bundle arrangement of fibrovascular elements. 1. Xylem. 2. 

 Endodermis. 3. Phloem. 



C. Bicollateral Bundle arrangement of fibrovascular elements. 1. Phloem. 

 2. Cambium. 3. Xylem. 4. Cambium. 5. Phloem. 



D. Open collateral type, Aconite tuber. 1. Bast fibers. 2. Sieve cells. 3. Cam- 

 bium. 4. Wood fibers. 5. Ducts. 6. Medullary ray. 



E. Open Collateral Bundle arrangement of fibrovascular elements. 1. Phloem. 

 2. Cambium. 3. Xylem. 4. Medullary ray. 



F. Radial type, Sarsaparilla root. 1. Endodermis. 2. Sieve surrounded by 

 bast fibers. 3. Wood fibers surrounding sieve and ducts. 4. Ducts. 



G. Radial Bundle arrangement of fibrovascular elements. 1. Endodermis. 

 2. Xylem. 3. Phloem. 4. Pith. 



H. Concentric type, Fern rhizome. 1. Endodermal sheath. 2. Sieve sur- 

 rounded by small parenchyma. 3. Fibrous tissues. 4. Ducts. 



/. Concentric Bundle arrangement of fibrovascular elements. 1. Endodermal 

 sheath. 2. Phloem. 3. Xylem. (From C. W. Ballard's "Vegetable Histology," 

 Courtesy of John Wiley & Sons.) 



(the tiny divisions in the cell of 

 important structures in synthesis 



B 



Fig. 140. Assimilating and Synthesis Tissues. 



A. Plastids (chloroplasts) in a cell. 



B. Diagram to illustrate the processes of 

 breathing, food-making, and transpiration 

 which may take place in the cells of a green 

 leaf in the sunlight. (After Stevens.) 



plants which contain chlorophyl), are 

 by converting (when in the sunlight) 

 carbon dioxide and other sub- 

 stances into starches and sugars; 

 and the Leukoplasts (similar struc- 

 tures which do not contain 

 chlorophyl), by assisting in form- 

 ing storage or reserve-starch from 

 the sugar manufactured by the 

 chloroplasts. 



Secreting cells and hairs which 

 are really structures quite like the 

 glands of animals. 



Storage Tissues (Fig. 141). In plants which continue their life 

 throughout many seasons, there must be a method of storing the food 



