FEEN 325 



of the indusium ? Size ? How is it attached ? 

 What changes take place in it as it de- 

 velops? Draw a single pinna, showing both 

 surfaces. 



Look for young fronds and notice the manner 

 {circinate) in which they are rolled up in the bud. 



Microscopic Structure. 



a. The rhizome. — Cut a series of transverse sections 

 of the rhizome, mount the thinnest and most per- 

 fect in a drop of water or dilute glycerine, and 

 examine under the low power. Make out the fol- 

 lowing parts : on the surface a single layer of 

 cells, the epidermis ; within this a band of dark- 

 brown cells, sclerenchyma ; enclosed by the 

 band of sclerenchyma, a ground mass of light-col- 

 ored cells, parenchyma ; embedded in the par- 

 enchyma, isolated groups of sclerenchymatous 

 tissue and large masses of yellowish tissue, the 

 fibro-vascular bundles. 

 Make a diagram showing the position of all these 

 parts. Put on the high power and study each of these 

 in detail. 



1. The epidermis. — How many cells in thickness 

 is it ? What is the shape of the cells ? What 

 do they contain? How do the different walls 

 of an individual epidermal cell compare in 

 thickness? Examine sections in which the 

 margin is perfect, and note whether or not the 

 epidermis is always present. Does the epider- 

 mis present any outgrowths? If so, what are 

 they? Is the epidermis broken at places to 

 allow of the passage of outgrowths from under- 

 lying tissues ? Draw a portion of the epidermis. 



