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as to present at least twice this amount of surface. This 

 is effected by the very small, proportionately high pro- 

 tuberances between the veins. In a recent article*) by 

 Prof. Kny, it is claimed that these little elevations found 

 on the blades of various leaves are especially adapted 

 to protect the leaf from the injury to which it is exposed 

 from the force of the falling rain or hail. In this con- 

 nection, however, we have to do only with the increased 

 amount of surface thus provided with living active cells ; 

 one other fact may also be mentioned here, that is, that 

 these living cells are in this way protected from the 

 pressure of the surface filz, the cells of the latter lying, 

 for the most part, horizontally across from one to the 

 other of these protuberances. The stomata which here 

 occur on both sides of the leaf are surrounded by an 

 atmosphere doubly protected, that is, by lying in these 

 little cavities, as well as by the filz-covering. 



One of these lower leaves, a little under the medium 

 size was allowed to wilt rapidly, exposed to sun and 

 wind, after having been separated from the plant, till 

 it was completely limp, then held by the petiole and 

 lightly brushed, first on the upper, then on the under 

 surface, with water. In about five minutes, water having 

 been several times lightly applied, the leaf began to 

 stiffen so it was perceptible to the feeling, it being yet 

 in the hand. Ten or fifteen minutes later it was as fresh 

 and stiff, as when picked from the plant. This was the 

 most rapid and remarkable action obtained. The ex- 

 periment was repeated with leaves of various sizes taken 

 from the same plant, the result was always the same, 



*) Bericht der deutschen Bot. Gesellschaft. Jahrgang 1885 

 Band III, Heft VI. 



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