68. 



loses water most rapidly#It is needless to say that when 

 an appreciable amoimt of water is lost, a, folding or a 

 curling of the leaf results. In both living and dead leaves 

 those of which neither surface was sealed, curled up 

 completely when subjected to dry conditions; those of which 

 only the lower side was sealed curled not quite as markedly 

 as in the former case; the leaves of which the upper side 

 only v/as sealed became only partially folded;while those 

 with both surfaces sealed remained completely expanded 

 throughout the experiment, The condition of the living leaves 

 remained unchanged in the jar containing 10^ acid and in 

 the one contanining distilled water indicating that there 

 was no loss of v/ater from the leaves .The killed leaves, however, 

 failed to show any loss in weight even in the jar containing 

 25^ acid.Furthermore, these soon became infected by a fungus 

 in the jars contaings 25^ and 10^ acid as w^ell as in the one 

 containing pure water. 



The results of the experiments on the water losing 

 power of the leaves, which show that the lower surface 

 loses water about twice as rap^'Jy as the upper ^discredit 

 at once the idea that the protection of the upper surface 

 by curling is a very effective adaptation ac&inst excessive 

 trans pi rati on, The rolling inward of the upper surface does, 

 of course, reduce the transpiring area in half , but it leanres 

 the more active half, which contains all of the stomata, still 

 exposed.The question, then, exises whether the lower surface 

 might not really be especially capable of water absorption 



