E. TISSUE SYSTEM (of Sachs). 



1. Epidermal Tissue System. 



2. Fibro- Vascular Tissue System. 



3. Fundamental Tissue System. 



i. The Epidermal Tissue System. 



Tissues Covering the EXPOSED SURFACES of Plants. Epidermal 

 Cells and their Modifications. 



Illustration First : EPIDERMAL CELLS, STOMATES, and TRICHOMES. 



For this study examine the notes and drawings made on p. 83. 



Illustration Second : EPIDERMAL CELLS and FORMATION of 

 STOMATES. A very young leaf of a " STONE CROP," (Echcveria 

 secunda-glauca), or Sedum ternatum. 



PREPARATION: With a razor make a thin section parallel to 

 lower surface of leaf, extending from the middle to the base, and 

 including the Epidermis and a little parenchyma. Mount sections 

 in water. 



OBSERVE : 1. The epidermal cells of irregular forms, without 

 chlorophyll, the outline distinctly sinuous. 



2. The stomates, oval or nearly circular when fully formed. 



3. The guard cells of a stomate ; lunate in form and contain 

 ing grains of chlorophyll. 



4. The Pore of the Stomate. 



5. The several stages of development in the- </<>";/ or form 

 iny stortiMtes; beginning with the initial cell and ending with the 

 " mother cell " of the stomate just split into the two " guard cells." 

 The various septa even the primary one may be distinguished 

 from the original epidermal cell- walls by their straight or curved 

 (not sinuous), lines. 



