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by these cells, provided the cell sap possessed sufficient 

 osmotic force. 



It is not meant to be assumed here that this force 

 corresponds to that of a ten per cent salt solution. It 

 is probably much less, the solution was made of this 

 strength for convenience in working. The time actually 

 required by the leaf to perform this work is of minor 

 importance, as the water held by the hair meshes would 

 be effectually hindered from evaporation, therefore could 

 more slowly enter the leaf tissue. 



Phlomis Busseliana Lag. has a similar filz and acts 

 in the same manner in reference to absorbing water. 

 The hair may be described as several storied, the stem 

 branching several times. The walls of the branches are 

 not much thicker than those of the stem, but they often 

 contain air. Experiments with the salt solution showed 

 that the cells between the epidermis and the first set of 

 branches were living, also many of the upper ones of 

 the stem. Some of these latter, however, did not react 

 and some contained air. The pores here are very notice 

 able, occurring between the cells of the stem, as well 

 as where the branches join it. 



The hair forming the filz of Arabia albida is some- 

 what remarkable for its size and simplicity of structure. 

 The stem is one long cell averaging about 360 mik. in 

 length, 45 in diameter. For about one fourth of its 

 length this stem is entirely solid, the lumen extending 

 only through the lower part, terminating above in a sharp 

 pointed cone; the wall below is rather thick, the dia- 

 meter of the hair being so great the lumen is still of 

 considerable size. The lower end of this stem cell is 

 surrounded by eight or nine raised epidermal cells, with 



