*l* MAIDEN-HAIR FERN. 



detail each of the tissues and groups of tissues seen above, 

 in the following order : 



6. The epidermis. Observe 



a. That the outer wall is thicker than the lateral and 

 inner ones. In favorable sections a very thin 

 layer, the cuticle, may be seen covering the outer 

 wall. 



b. That the epidermal cells contain numerous round- 

 ish or somewhat angular starch granules? Treat a 

 freshly-cut section with iodine, and notice the 

 color produced. 



i. Study one of the starch grains. Notice the 

 central lighter spot, the nucleus. 6 



c. Draw several epidermal cells. 



7. The sclerenchyma, peripheral and axial. Note 



a. How greatly the walls are thickened. 



b. That adjoining walls consist of three or more dis- 

 tinct layers, the thin central one of which is the 

 middle lamella. 



c. The perforations or pits, which extend through the 

 thickening layers to the middle lamella at right 

 angles to the surface of the wall. Observe that 

 the pits in contiguous cell walls correspond to 

 one another. 



d. Examine the middle lamella at a point where three 

 or four cells meet. Note that it divides, inclosing 

 a triangular or quadrangular space which is filled 



4 The occurrence of starch in epidermal cells is unusual. 



6 The term as here used has an entirely different signification from 

 that which it has as applied to a cell. Here it denotes a central watery 

 spot, about which lie the layers of the starch grain, alternately more and 

 less watery. 



