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in water showed a silvery coating over the filz, which 

 shows the existence of a layer of air between the water 

 and the surface of the hairs. In many instances this was 

 rapidly absorbed by the water and after a few minutes 

 the hairy surface appeared evenly wet. Other examples 

 were less easily affected and retained the air layer for 

 several hours, the leaf appearing perfectly dry, when 

 at the end of this time it was removed from the water. 

 None were examined where this hindrance to the en- 

 trance of water was not removed by allowing the leaf 

 to lie some time in water. In all cases where the leaf 

 was really filzig, wax was not present in sufficient quan- 

 tities to be detected with the microscope. 



The second assumption, namely, that the endos- 

 motic force of the living cells is sufficient to draw the 

 water into the leaf tissue, can be proven only by ex- 

 periment and a few examples will best show what de- 

 gree of certainty was reached. 



Before entering upon a description of these examples, 

 a few words are necessary in explanation of what has 

 already been asserted. It is usually claimed that the hairs 

 of this filz are without contents, or that they contain only 

 air*); also that in some cases they are not covered by 

 a cuticle**). The former is strictly true only of those 

 leaves which we have placed in the third class. This 

 contains a large portion of the leaves under consideration, 

 but by no means so large a part as the first and second 

 classes combined. In these two classes a portion of the 

 hair is living and contains active protoplasm as has been 

 demonstrated by the action of the primordial „schlauch". 



*) De JBary. Vergl. Anatomie. Page 73. 

 **) Tschirch Linnaea B. 43. H. 3 and 4. Page 152. 



