138 



MINUTE STRUCTURE OF THE STEM. 



cases can generally be referred to eccentric growth of some one 

 or more parts, as in flattened stems, or explained by the intro- 

 duction and more vigorous growth of supernumerary bundles. 



394. Extraordinary anomalies are afforded by the Hones of 

 tropical countries, woody climbers with distorted stems. They 

 belong chiefly to a few orders; namely, Bignoniacese, Mal- 

 pighiaceae, Menisperniaceaj, and Aristolochiacese. A few inter- 

 esting cases are shown in the accompanying figures, and are 

 sufficiently explained in the descriptive letter-press. 



i" 



116 



395. Spring wood and autumn wood. The secondary wood an- 

 nually produced in a temperate climate like ours exhibits certain 

 differences between the inner and the outer portion of the }-ear's 



FIG. 113. Transverse section of the stem of a liane belonging to the order Malpighi- 

 acese : m, pith ; b, the central portion of the wood, arranged in concentric layers around 

 the pith. (Duchartre.) 



FIG. 114. Transverse section of the stem of a liane belonging to the order Malpighi- 

 acese: m, the pith. The bark follows all the irregularities of the wood. (Duchartre.) 



FIG. 115. Transverse section of a liane belonging to the order Sapindacese: b, pri- 

 mary woody body having its own pith m, and bark e'c; b', b', &', three secondary woody 

 bodies without pith, but having as thick a bark as the primary body. (Duchartre.) 



FIG. 116. Transverse section of the stem of a liane belonging to the order Sapindaceas : 

 b, the primary or central woody body having its own pith m ; //, b', b', b', a circle of un- 

 equal secondary woody bodies; b", tertiary woody bodies. (Duchartre.) 



