02 MOSS. 



a. The shape of the cells. Draw. 



b. The direction taken by the leaf traces. 



Remove the scales from a stem, cut a slice from the 

 surface, and notice 



7. The shape of the epidermal cells. Draw. 



D. THE LEAF. Make a transverse section just below the 

 middle of one of the largest foliage leaves, and notice 



1. The larger central portion, the midrib. 



2. The plate of cells, usually a single row, extending right 

 and left from the midrib, the lamina. 



3. The midrib. Note. 



a. The epidermis : a single layer of cells on the con- 

 vex (under) side ; a layer on the flat (upper) side, 

 each cell of which gives rise to a vertical plate, 

 two to four or more cells in height. If from a 

 fresh specimen, note the contents of the cells. 



b. The leaf bundle; compare the several parts, the 

 dorsal, basal, central and conducting cells, with the 

 corresponding parts of the leaf trace which enters 

 the stem, already examined. 



c. Occasionally a few cells between the dorsal and 

 basal cells and the adjacent epidermis, resembling 

 the latter. 



d. Draw the midrib. 



4. The lamina. Note 



a. The shape and contents of the cells. 



b. The smaller grouped cells at the margin of the 

 lamina. 



c. Draw. 



Mount a foliage leaf entire with the upper side upper- 

 most, and beside it another with the lower side, uppermost ; 

 using low power, notice 



9 



