6 8 COMMON LI VER WOR T. 



and the over-arching roof formed of the single epider- 

 mal layer of cells. Draw. 



When a section is found which has passed through a 

 stoma, notice 



15. The chimney-like structure, the number of cells in 

 depth, and the shape of the cut ends of the cells, es- 

 pecially of the outer and innermost ones. Draw. 



16. Illustrate the structure of the stem as shown in the 

 longitudinal section by a diagram. 



17. Cut a vertical section of the wing at right angles to the 

 longitudinal one already examined, and compare with 

 it : especially note the difference in the outline of the 

 parenchyma cells, and the frequent absence of reticu- 

 lated markings. Draw. 



C. THE LEAF. Remove a leaf from the stem, best 

 taken from a young stem where the leaves are comparatively 

 large and conspicuous, and notice 



1. The shape of the cells, absence of markings and of 

 chlorophyll, and the uniformity of the cells throughout 

 the leaf. Draw. 



Make a transverse section of the stem at right angles to 

 the midrib, and a good transverse section of the leaves will 

 usually be obtained : notice 



2. The single row of cells forming the blade, or some- 

 times two or three rows at the base, and the manner in 

 which the older leaves over-arch the younger. Draw. 



D. THE CUPULE. Remove a cupule and place face 

 upward on the slide, ignoring for the present the gemmae 

 which float out from it ; press the cover-glass down until the 

 cupule is sufficiently flattened ojit, when it will appear as a 

 wide ring of tissue, the bottom of the cup having been cut 

 away. Examine with low power 



