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the leaves were turned, not completely over, but so far 

 as to screen the upper surface effectually. Frequently 

 leaves of the same branch, not more than three feet in 

 length, were found to vary in this respect, those near 

 the end being turned from their normal position, while 

 the others nearer the body of the tree grew straight on 

 the stem. This peculiarity is the more striking as this 

 species is considered less sensitive to climatic influences 

 than either of the other two where the leaves all have 

 the normal position. These facts seem to indicate the 

 protection of the chlorophyll from the influence of the sun, 

 which is effectually rendered by the chlorophyll-filled 

 pallisade cells being thus turned away. The hair covering- 

 may add to this effect, as it is not impossible that in this 

 way the rain drops are secured and drawn into the horns 

 by the agency of the thin air. 



Several species of Qnercus have filz corresponding 

 to that of Tilia in structure, except the cell walls are 

 usually thicker, and in one species, Quercus Fordii, there 

 is a decided stem. Two other plants are placed in this 

 class whose anatomy varies from the two types described 

 by the presence of a stem, Shawia paniculata Forst. and 

 Lavendula vera Benth. In the stem of the latter the 

 wall is so thickened as to leave but a small lumen, while 

 in Shawia there is often no lumen. The wall consists 

 here of two layers of different chemical nature as is 

 shown by the action of reagents, as well as by the 

 difference in color and light breaking without the appli- 

 cation of reagents. All plants placed in this class agree 

 in having no living cells in the hair. 



In addition to those placed in these three categories, 

 quite a number were examined, which although strictly 



