102 NATURE-STUDY LESSONS. 



XXVI.-THE MAPLE TWIG, FLOWER AND FRUIT. 

 A. The Markmss and Their Significance. 



1. (a) Examine a branch from a maple-tree. 

 (d) What markings are found on this twig? 



(c) Show the bud-scale scars. 



2. (a) Show the part which grew last year. 



(d) Explain your reason for selecting this part as 



that which grew last year. 



3. Describe the other markings. 



4. Compare the markings on a maple branch with 

 those on a horse-chestnut. 



5. Infer the cause of these marks. 



6. (a) Cut the part which grew last year, across at 



right angles to its length. 



A section or cutting at right angles to the length of the branch is a 

 cross-section. 



A thin section cut along the diameter is called a radial longitudinal sec- 

 tion, and one cut lengthwise across the diameter and towards the outside is 

 called a tangential longitudinal section. 



The spongy central part is called the pith or medulla. 



(b) Describe the cross-section particularly. 



(c) With a pin or sharp-pointed knife examine 



the central part. 



7. With a sharp knife make the three kinds of sec- 

 tions. Describe each. 



8. Distinguish the three areas — bark, wood, pith. 



9. Take a fresh stem and identify the line of separation 



between the bark and wood in the cross-section. 



The cylinder of soft, spongy tissue in the centre of the branch is the 

 pith. It is composed of celliUar tissue. The outside layer of the branch 

 is the bark. 



The hard, solid part of the branch between the pith and the bark is 

 wood. It is composed of tissue made up of ivoody fibres and vtsscls. 



