120 MAIDEN-HAIR FERN. 



of the leaf, will be seen three or four very thick-walled 

 cells. 



6. Draw the vertical section of the leaf. 



Bend a leaflet over the finger and cut the thinnest possi- 

 ble slice from the under surface lengthwise of the veins. 

 Mount with the cut surface upward, and note 



7. The length of the cells over the veins and the manner 

 of overlapping, fibrous tissue, Draw. 



8. The trichomes in the form of sporangia. Scrape some 

 sporangia from a sorus of a dried specimen, examine 

 dry with a low power, and note 



a. The shape and color. 



b. The row of brownish walled cells extending part 

 way around the sporangium, the annulus. 



c. The stalk by which they were attached. 

 Examine with a high power sporangia from alcoholic 



specimens, mounted in water with cover, and note 



d. The structure of the wall of the sporangium. This 

 can be best studied in some of the immature spor- 

 angia which can usually be found in the same sorus 

 with the mature. Supplement this study by exam- 

 ining the wall of a bursted sporangium. Observe 

 that the wall consists of a single layer of much 

 flattened cells. Note the nuclei. 



e. The annulus. Study the cells which compose it. 

 Notice that it forms a distinct ridge and is cpn- 

 tinued beyond the point where the cells are thick- 

 est by a series of short broad cells with thinner 

 walls. 



/. The stalk ; the number of cell rows which com- 

 pose it and the absence of any trace of a fibro- 

 vascular bundle. 



