BRANCHED HAIRS. 93 



Branched multicellular hairs are to be found in the same 

 plant on the under side and edges of the corolla. Seen from 

 above, these hairs have a certain likeness to those of Matthiola, 

 but all of the branches here arise from a common central 

 point, and each branch is in itself a closed cell. Moreover, the 

 branches do not spread out in the same plane, but arise at 

 indefinite angles. Their walls are quite as strongly thickened as 

 in Matthiola ; outer protuberances are wanting. The hairs on 

 the edges of the petals are seen in side view. The body of the 

 hair is cut off by a partition wall from the epidermal cell which 

 bears it. It consists of a stalk or pedicel, almost always uni- 

 cellular, and upon this the branches are mounted. Slight 

 modifications of these conditions occur, which need no further 

 explanation. Besides these branched hairs, the edge of the 

 corolla also bears small glandular hairs. These have a two to 

 three celled stalk, and a flattened head, which is covered here 

 and there at the apex by a strongly refractive substance. These 

 last we shall 'not, however, study here, but in another more 

 favourable object. 



Felted Hairs of Mullein. It is only necessary to imagine the 

 multicellular branched hairs of the Mullein placed one upon 

 another several times, in order to understand the hairs which 

 form the felt on the leaves of Verbascum thapsiforme. These 

 hairs are sometimes as many as five stages high, each stage 

 separated from its predecessor by a unicellular joint, which 

 continues the main axis of the hair. The cells of the hair are 

 for the most part filled with air. They are best shown by cross- 

 sections through the midrib of the leaf. 1 



Scales of Shepherdia. To the same category as the branched 

 hairs of the petals of Verbascum belong the scales of Shepherdia 

 canadensis, a hardy ornamental Elaeagnaceous shrub. On the 

 under side of the leaf, distinguishable even with a hand lens, 

 we find more or less loosely constructed white, and more or 

 less closely constructed brown (Fig. 35, A) stars. On the upper 

 side of the leaf only white stars are to be found, and always in 

 smaller number. The cells of these looser white stars contain, 

 as microscopical examination shows, only air ; they arise from a 

 common central point, but are separated from one another later- 

 ally. On the upper side of the leaf they do not lie in one plane, 



1 Verbascum Tliapsus, a native perennial, has very similar hairs. [Eo.] 



