140 



BOTANY 



PAET I 



the interfascicular cambium may still be plainly distinguished. All 

 the tissue arising from the inner side of the cambium ring goes to 

 form the secondary WOOD, while that produced on the outside is 

 termed secondary BAST. The primary and secondary wood together 

 form the wood, the primary and secondary bast the bast of the stem. 



Fig. 148— Transverse section of a stem of Aristoloch id Sipho in the lirst year of its growth, showing 

 a vascular bundle with cambium Ju active division, p, Vascular parenchyma ; rip, iiroto- 

 xylem ; m' and m", vessels with bordered pits; ic, interfascicular cambium in continuation 

 with the fascicular cambium ; v, sieve-tubes ; chp, protophloem ; pc, pericycle ; sk, inner part 

 of ring of sclerenchymatous fibres, (x 130.) 



In contrast to the primary cortex (p. 128), all the tissues to the 

 outside of the cambium may be regarded as forming secondary cortex. 

 The vascular portions of the wood form the wood strands, the sieve 

 portions within the bast the bast strands. By the activity of the 

 interfascicular cambium, the primary medullary rays are continued 

 throughout both the wood and bast. As the wood and bast strands 

 enlarge, SECONDARY mp:dullary rays are developed from the 



