— 21 — 



veins where the extremely large hair cells are ready to 

 absorb it. Here it could pass at once into the cir- 

 culation without the necessity of first passing through 

 the parenchym cells. 



On experimenting with this leaf, it was found that 

 by brushing the veins alone on the under side with water, 

 the leaf absorbed the water about as rapidly as the Salvia 

 leaf described. The surface between the veins also ab- 

 sorbed water but less rapidly. 



The greater number of the leaves of this class were 

 tested with greater or less thoroughness in reference to 

 their readiness to absorb water when applied to the sur- 

 face. Some few cases occurred where the action was 

 very slow. For example, Centaurea argentea L. Of the 

 whole class only one was found which refused to act 

 in this way. A leaf from Onopordon tauricum Willd. 

 from the botanical garden in Zurich, when allowed to 

 wilt, then brushed with water, remained limp and wilted, 

 placed directly in water and allowed to remain for several 

 hours it still showed no signs of turgescence. The ana- 

 tomy of this leaf, however, is very similar to that of 

 those already described, several large living hair cells 

 below, covered with rather a light filz. Stomata somewhat 

 raised. A very good explanation for this apparently 

 contradictory result may be found in the fact that the 

 leaf was examined in September after the plant had 

 finished its summer's growth. The hypothesis rests entirely 

 on the supposition that the cell sap of the epidermis and 

 hair-cells has osmotic force sufficient to draw the water 

 through their walls. It is not impossible that in this 

 instance, the chemical nature of the cell sap had under- 

 gone some change by which this force was so diminished 



