112 Elementary Work in Botany. 



represent the medullary rays, which are prominent in oak, 

 causing the peculiar grain shown on the surface of boards 

 which are "cut with the grain." The significance of the 

 commercial term " quartered oak " is evident. The diagram 

 shows plainly the difference between lumber from the center 

 of a tree and that from near the surface. The following 

 and many more questions should arise : 



What part of a log will give " clear-stuff" (boards with- 

 out knots)? Which furnishes the most clear-stuff, large or 

 small logs ? Explain. How many years older is one edge 

 of your desk than the other? How do you determine? 

 Where is the oldest wood in a tree ? The youngest ? Is a 

 knot which pierces a board older or younger than the 

 remainder of the board ? Explain. What causes the wavy 

 lines on some of the boards used in making your desk ? 

 Find the oldest wood in one of these boards. Where was 

 the center of the tree from which it was cut ? Does red- 

 wood split easier along the layers of growth or along the 

 .medullary layers? It might split more easily through the 

 center and yet the adhesion between the seasonal growths 

 be less than that between layers separated by medullary 

 rays. Can you explain why ? 



NOTE-BOOKS AND PENCILS. 



Pupils should have good pencils and note-books. Notes 

 taken with a cheap pencil on inferior paper enclosed by 

 paper covers are likely to be as worthless as the materials 

 used in recording them. Good tools and good material spur 



