Fig. 256. — Pinus: transverse section of phloem of the first year and older phloem. 

 Below the cambium (cells densely dotted) are a few cells of secondary xylem. There are 

 two medullary rays, the one on the right with cells containing starch, and the other with 

 no starch. There are four large cells, shown with nuclei and starch, two in the living 

 phloem and two in the dead. The rest of the dotted cells are living sieve tubes; the cells 

 above them, which have lost their contents, are sieve tubes of the preceding year. The 

 lines looking like protoplasmic connections indicate the sieve plates. In the dead 

 phloem, they are covered by the callus, shown in black. — After Jeffrey.^"' 



