40 STUDY OF COMMON PLANTS. • 



studied. Show how the stem of a monocotyledon, such as 

 Indian corn, differs from that of the apple-tree and other 

 dicotyledonous plants. With which do the stems of the 

 conifers (pine, arbor vitae, etc.) agree ? 



v. Ascertain the age of specimens of white oak, hickory, 

 ash, pine, and Norway spruce, by counting the annual 

 rings. The work 'must be done with care, in order to 

 insure accuracy. In examining large sections, draw a 

 straight line from the center to the periphery, and mark 

 off on it intervals of exactly one inch, beginning on the 

 outside. Count the number of rings in each division and 

 record them in their order. Compare the rapidity of 

 growth of the pine and spruce ; of the ash and hickory .^ 



MINUTE ANATOMY. 



I. Take fresh shoots of the apple-tree, and cut a number 

 of transverse sections. Mount some in water, others in 

 glycerine, and still others in Schulze's solution for micro- 

 scopic study .^ Examine first with the low power. Tak- 

 ing the parts in order, beginning with the outside, we find 



1. The outer bark, or cork, consisting of several layers 



of flattened cells with reddish-brown contents. 

 (The remains of the epidermis outside of the cork 

 may be disregarded.) 



2. The middle bark, or cortical parenchyma, consisting of 



a broad zone of cells with green contents (chloro- 

 phyll). Near the inner edge of this zone are 

 bundles of thick-walled elements, bast fibers. The 



1 Other species may of course "be used if more convenient. 



2 The success of the work depends upon having good sections to study. 

 Worthless ones must he thrown away, and sectioning continued until 

 entirely satisfactory specimens are obtained. 



