358 



MANUAL OF BOTANY 

 Fig. 743. 



Fig. 743. Diagi-am of stem of Dicotyledon at three ages. a. Young condi- 

 tion showing commencement of differentiation of the stele and its fibro- 

 vascular bundles, a. Procambium bundles arising in 6, the stele, c. Cortex, 

 771.7". Medullary ray. pi. Pith. b. A little older stage, p. Phloem, 

 X. Xylem. c. Fascicular cambium, i.e. Interfascicular cambium. One of 

 the bundles has been shaded, c, Older stage after the commencement of 

 secondary thickening, ^^a;. Protoxylem. .r. Secondary wood. p7i. Secon- 

 dary bast. a. Kew bundles formed by the interfascicular cambium in the 

 primary medullary rays. The secondary medullary rays are indicated by 

 the black radial lines in the bundles. After Sachs. 



