THE STUDY OF TREES. 



253 



CORK 



THE STUDY OF A TWIG. 



It may be pointed out at the commencement that twigs 

 may be regarded as small stems, since their functions are 

 in general the same. The most satisfactory times at which 

 to study them more particularly are probably spring and 

 winter. 



We hold in our hand a Winter twig of a Sycamore tree. 

 What can we do with it ? What can we learn from it ? 



First let the pupils draw the twig natural size, colouring 

 it, and filling in markings, etc. Pupils should be encou- 

 raged to perform this exercise reflectively, mentally framing 

 questions to be raised later. 



Next let us frame a verbal description. What is the 

 general habit of our twig ? The twig is straight, cylin- 

 drical, robust, about 



a quarter of an inch EPIDERMIS LOOSE CELLS 

 in diameter in its in- 

 ternal section. What 

 is its colour? My 

 twig is ten inches 

 long, and I recog- 

 nise a terminal por- 

 tion about 4J inches 

 lighter than the rest. 

 This terminal por- 

 tion is brownish in 

 colour, with a dis- 

 tinct suggestion of 



greenness. I peel off a little of the bark here, and find 

 that it is light brown with 110 green. Beneath it, however, 

 the tissue of the twig is green. The other portion of the 

 twig is darker brown, with no perceptible greenness, and 

 here we see the bark is thicker, so that .the green under- 

 lying tissue does not show through. 



There is a little gloss upon the bark, but this is not 

 uniform ; it is thickly dotted with lightish spots, which 

 form little elevations in shape longer than broad, 

 examine these with a pocket lens. On the older parts of 



CORTEX 

 Fig. 128. Section through a lenticel, magnified. 



