Lecture XXII. 191 



lem, primary wood, primary bast and protophloem should also be shown. 

 The resin-ducts will also be conspicuous. 



Prepare and mount transverse sections of a part of the stem which is 

 two or three years old. Make an outline sketch of the whole. Fill in details 

 on a sector of the sketch, showing the pith, the protoxylem, the primary wood, 

 the primary medullary rays, the spring and summer wood of the two or three 

 rings, the secondary medullary rays, the cambium, the secondary bast, the 

 primary bast (the protophloem cannot be recognised) and the secondary cortex. 



Transverse sections of the young growing tip of the root and of part which 

 is two or three years old should also be prepared. Notice -the change of the 

 prismatic, or grooved, core of primary wood into a solid cylinder by the 

 addition of new wood. The position of the protoxylem at the angles of the 

 primary wood may be easily identified by the well-marked primary medullary 

 rays which are directed radially inwards from the cortex, and terminate at the 

 protoxylem. 



