11 



The results of the comparison of these three classes 

 show that, in general, the leaves of the first class are 

 best fitted to absorb the water, either rain or dew, 

 which may adhere to the rough surface of the filz. Several 

 of the second class appear to absorb water as readily 

 as any of the first, but the number is proportionately 

 smaller than in the first class. In the third, it is question- 

 able whether this can in any single case, be considered 

 the chief function of the hair, though the possibility of 

 its contributing in a greater or less degree to this result, 

 is by no means excluded. 



Beginning with the first class, some few cases occur 

 in which the hair has nearly the same diameter throughout, 

 consists of only two cells, the first, that is the one cut 

 off next the epidermis, is nearly isodiametric, the second, 

 extremely long and either thick-walled and round, or 

 having lost its contents, flattened by the pressure of the 

 air from outside. In the former case the separate hairs 

 are coiled spirally so that a very firm elastic coating is 

 formed by their interlacing. In the latter, the separate 

 hairs are occasionally twisted but never coiled and the 

 filz is formed by their matting together instead of twisting 

 and coiling around each other as in the former case. 



The outer wall of the remaining epidermis cells, 

 those without hairs, corresponds generally in thickness 

 with that of the first hair cell. Examples are Teucrium 

 fruticosum L., Alfredia nivea Karel, Cerastium tomen- 

 tosum L., Petasites niveus Cass., one species of Cineraria 

 and two of Artemisia. 



It is easily seen that this filz might serve to fasten 

 or hold the water, either rain or dew, until by capillary 

 force it could be drawn between the meshes and so find 



