— 41 — 



and prove unquestionably the truth or falsity of the 

 assumption. 



Lastly we come to those cases where the raised 

 stomata lie in ridges or cavities, as Banksia, Dryandra, 

 Erica, Nerium, &c. These plants furnish the most popular 

 and well known examples of the power of nature to 

 adapt itself to unfavorable outward surroundings and are 

 every where quoted as examples of plants specially fitted 

 to endure long continued, as well as irregular seasons 

 of drouth. They are all found among the various forms 

 native to the Cape of Good Hope and those belonging 

 to the family Proteaceae are filzig. These are not in- 

 cluded in any of the three classes, because at the time 

 of making this study only a few fresh, living species 

 could be obtained and these unfortunately were not such 

 that experiments could be satisfactorily made. Quite a 

 number of dried specimens were examined and these 

 were covered with a thick filz protecting the openings 

 of the cavities where the stomata occur. 



In the cavities in the leaves of Nerium Oleander, 

 the arrangement of the stomata and hairs is such as to 

 suggest the power on the part of the plant to regulate 

 to a certain degree the amount of moisture in the at- 

 mosphere immediately surrounding the stomata. When 

 the soil contains moisture enough to allow free tran- 

 spiration and yet continue the supply, the superfluous 

 moisture may escape from the leaves slowly between 

 the meshes of hairs which loosely cover the openings. 

 When the supply from the roots is lessened, it is not 

 impossible that the contents of the epidermal and thin- 

 walled hair cells, acting together with the diminished 

 tension of the membrane, may be able to draw in the 



