70. 



about it is an unsettled question. It is certain that 

 no leaf actually came in contact with the liquid water 

 which covered the floor of the chamber, It is quite possible , 

 however, that during the night the water vapor was condensed 

 on the surface of the leaves so that the leaves may have 

 obtained the water entirely by the imbibition of the liquid 

 water condensed on their surf aces, and not by condensing 

 the water vapor that penetrated to the interior by v/ay of the 

 storaata#At any 3ate,it is noteworthy that the leaf increased 

 in weight nearly ten times as rapidly when the lower surface 

 was unsealed as when the upper one was left uncoated. Whether 

 this enormous increase in weight is due to the fact that all 

 of the storaata of the leaf are found on the under side of the 

 leaf and none on the upper side and thus'.dff er;Jiore absorbing 

 surface is a question that needs further investigation. 



The diiff^"">nce in the appearance of the leaf under 

 wet and dry conditions suggests that there may be internal 

 structural differences between the expanded form and the 

 curled one.Pairaff in sections were made of both curled 

 and expanded leaves fixed in absolute alcohol, These showed 

 a remau:kable difference in the tissues of the leaf»* The cells 

 of the expanded leaf seemed to be turgid and maintained 

 their maximum size and smooth outline, The cells of the curled 

 leaf, on the contrary, greatly reduced in size and wrinkled 

 in outline, The shape of a cross section of a curled leaf 

 is shown in Fig,22,The diagrammatic drawings in Figs. 23 and 

 24 show the comparative size and shape of the cells from 



