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as to render the cells inactive there being no longer 

 any necessity for their action. 



In the second class the anatomy of the hair is far 

 more complex, the construction of the leaf more varied, 

 so that the simple tests described, could not be so success- 

 fully applied. The leaves of several species are stiff and 

 leathery, these could not be tested by allowing them to 

 wilt. One very beautiful filz as far as the theory is con- 

 cerned, occurs on both sides of a thick fleshy leaf, Arabis 

 albida, here of course this test is out of the question. 

 Several were studied in September when the same reason 

 could be given for the leaf failing to absorb water rapidly 

 as that suggested for Onopordon. 



Still, quite a number may be cited, which were 

 thoroughly tested in the same manner as those of the 

 first class with equally satisfactory results. Such are 

 Phlomis fruticosa L., Lavatera oblongifolia, Phlomis Russe- 

 liana Lag. and others. In all the examples given in this 

 class the important characteristics are present, namely: 

 thin-walled epidermis cells, raised stomata and above 

 all, a large surface of thin-walled hair cells. These 

 compose the stems of the hairs, which consist in a few 

 cases of a single cell. Such are the hairs of Verbascum, 

 Arabis, Vesicaria &c. Generally the stem consists of a 

 cell body of considerable size three or four cells in dia- 

 meter and eight or ten in length. 



Lavatera oblongifolia has a thick filz on both sur- 

 faces of the leaf, especially is this true of the under sur- 

 face. This filz is composed of two sets of hairs ; the 

 larger ones have a stem surmounted with long rays or 

 horns projecting in all directions. Another set, lying 

 completely hidden under these, consists simply of these 



