364 



THE VASCULAR TISSUES AND TRANSPIRATION. 



their transpiring leaves. In very many lianes the cavities of the conducting vessels! 

 can be plainly seen with the naked eye. This is the case, for example, in the cross- 1 

 section of the liane represented in natural size in fig. 95 ^. A diameter of J mm. is 



• Portion of tne stem of a tropical Aristulochia. s Cross section of a liane-like Aristolochia. » Menispermum Carolinianum. 

 * Cross section of the twining stem of Menisvermuin (magnified). * Portion of a liane (probably an Asclepiad) gathered in 

 a tropical forest ; nat. size. 



not at all rare in passion-flowers and aristolochias, and, generally speaking, in moist 

 twining and climbing plants; whilst in many lianes the conducting tubes have 

 even been observed to be 0*7 mm. in diameter. 



