482 THE POPULAR SCIENCE MONTHLY. 



a felting of hairs encompassing the stem, in which water rises as 

 in a piece of filtering paper. Dicramim, undulatum, Climacium 

 dendroides, and Hylocomium splendens are among the species thus 

 furnished. These hair formations commonly resemble the root- 

 hairs, and might eventually he designated as of that class ; but in 

 single cases, as in Thuidium iamariscinum, they exhibit a jDeculiar 

 construction. The hairs are undoubtedly adapted to taking up 

 the water with which they come in contact. 



With the phanerogams, the plenteous absorption of water by 

 organs above ground is a rare phenomenon of adaptation, and is 

 limited to a number of epiphytes (Bromelacice) and desert-plants. 

 In these, again, different forms of hair-growth assist the reception 

 of water. Volkens * has recently shown that many of those desert 

 species whose leaves are furnished with a hair-felting absorb rain 

 and dew in this manner. But he has never observed the reception 

 of the water going on over the whole surface of the hair, but only 

 in specific cells at the base of the hair which act as the absorbing 

 element ; while the dead cells composing the felt fulfill the pur- 

 pose of retaining the water, covering the surface of the leaf, and 

 in that way facilitating absorption. 



The capillary apparatus of the peat-mosses is peculiar and 

 without any analogies with the more highly developed plants. The 

 leaves of the Sphagnacece, consist of two kinds of elements; of 

 long-drawn, chloroiDhyll-bearing cells woven into a net-work, and 

 of dead, colorless capillary cells, which form the meshes of the 

 net. The walls of the capillary cells are furnished with large, 

 usually round pores, the points at which the water is admitted, the 

 situation and arrangement of which in many species materially 

 facilitate the passage of the water from one cell to another. The 

 edges of the pores are usually hemmed with a thicker fibrous ring, 

 the office of which is evidently mechanical, or to prevent tearing. 

 The walls of the cells are also stiffened with spirally arranged 

 fibrous structures, like the duct-walls of the more highly developed 

 plants. The stems of the peat-mosses have also a " bark-envelope " 

 from two to four cells thick, which serves as a reservoir and a 

 medium for the circulation of water. 



The stems, fruit-stalks, and leaves of numerous mosses pos- 

 sess a water-bearing tissue-cord occupying an axillary position. 

 This cord, which consists of narrow, thin- walled, and elongated 

 cells, has been described by W. Ph. Schimper and Fr. Unger, to 

 whom we owe some excellent researches on the anatomy of the 

 mosses. Its precise physiological function has until very recently 

 not been made clear. While it was not doubted that it had some 

 connection with the circulation, it was not certain whether or not 

 it presented any analogies with the vascular system of the higher 



* " The Flora of the Egypto- Arabian Desert." Berlin, 1887, p. 32. 



