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lacing cells or hair branches. In general, this may arise 

 in two ways, either from the coiling or matting together 

 of long hairs, consisting either of one long cell, or of 

 a single cell row, or the filz may be formed by the 

 interlacing of the horns or branches of the so-called star- 

 shaped or branched hairs. 



The greater number of leaves examined, however, 

 may be placed in three categories according to the 

 supposed physiological characteristics, as well as the 

 anatomical structure of the hair covering. The first class 

 includes those leaves with hairs consisting of cell rows, 

 whose first basal cell or cells are living and thinwalled, 

 the remaining part of the hair consists of one long, 

 thickwalled or dead cell. 



Second class : hairs whose bases or stems consist of 

 cell bodies of greater or less diameter (in a few cases 

 of a single cell), the cells composing this basis are living 

 and thin-walled, while the remaining portion consists of 

 long thick-walled cells. Third class: hairs varying in 

 anatomical structure but showing throughout noap pear- 

 ance of life. 



In addition to these are a small number which cannot 

 be so classified, some of which are so heavily coated as 

 to be strictly filzig, others on the limit between filzig 

 and ordinary hairy leaves. 



The three classes are as follows. 



I* Class. 



1. Petasites albus. 

 Shady places and 

 woods in Europe, Al- 

 giers. Subalpine. 



LIST. 



2. Petasites niveus. 

 Alps of Europe. 



3. Centaurea ar- 

 gentea. 

 Crete , on rocks 

 or dry places. 



4. Helichrysum 

 graveolens. 

 Tauris and Cau- 

 casus, South Russia 

 only. 



