228 



PRACTICAL BOTANY. 



M 



a continuous though somewhat irregular ring around the 

 stem. A is the pith parenchyma. 



Cut transverse sections of the Geranium stem and ver- 

 ify the figure. In what parts do you find chlorophyl? 

 Starch ? In the cortical parenchyma find crystals. Treat 

 with acetic acid. If the crystals are composed of carbon- 

 ate of lime, they will dissolve with effervescence ; if they 

 are composed of oxalate of lime, they will not be dissolved. 



If the crystals are 

 not affected, treat 

 with hydrochlo- 

 ric acid. This 

 acid dissolves the 

 carbonate of lime 

 with efferves- 

 cence; it dissolves 

 the oxalate of 

 lime without ef- 

 fervescence. 



Treat a section 

 of Geranium stem 

 with Schultze's 

 solution. What 

 portions are com- 

 posed of normal 

 and what of lig- 



FIG. 147. Radial section of mature Yellow Birch. 

 M, M, medullary rays ; S, S, S, scalarif orm ves- 

 sels, (x 35.) 



nified cellulose ? Treat another section made from a fresh 

 green stem with dilute iodine. In what parts do you find 

 protoplasm? Do you find nuclei and nucleoli in any of 

 the cells? In what parts do you find starch? Look for 

 intercellular spaces, using high power, if necessary. Where 

 do you find them ? Under high power study the cell walls 

 of the large vessels in the xylem ; also in the phloem. 

 Make out three layers in the wall. 



4. Cut longitudinal radial sections of the Geranium 



