176 PRACTICAL BOTANY. 



cal purpose may the elaters serve in the distribution of 

 the spores ? 



References for Reading. Goebel's " Classification of Plants," pp. 

 140-163; Vines' "Text-Book of Botany," pp. 324-354; Bennett and 

 Murray's " Cryptogamic Botany," pp. 132-136, 156-171 ; Strasburger 

 and Hillhouse's " Practical Botany," pp. 194-196, 272-277 ; Bower's 

 " Practical Botany," pp. 360-378 ; Dodge's " Practical Biology," pp. 

 308-319; Boyer's "Elementary Biology," pp. 134-139; Carpenter's 

 " The Microscope," pp. 590-594. 



CLASS II. The Mosses. The Lichens, Liverworts, and 

 Mosses are popularly but incorrectly spoken of as Mosses. 

 The true Mosses are distinctly higher in the complexity 

 of their structure than the Lichens and Liverworts. The 

 axis of growth is more erect ; the plant is provided with 

 truer leaves, with rhizoids that closely approach true roots 

 in character, and shows a greater differentiation in the 

 tissues of the stem. The cells on the outside of the stem 

 are elongated, are of a red-brown color, are thick walled, 

 and approach the structure of bark more nearly than any 

 tissues hitherto studied, though the epidermis is very im- 

 perfectly developed. Again the cells in the center of the 

 stem are thin walled, and are aggregated into a distinct 

 axial bundle, which, simulates in function, and to some 

 extent in structure, the fibro vascular bundles of all the 

 higher plants. The growth of the stem is by the division 

 of an apical cell which grows concealed in the leaves. 

 This cell has the shape of a triangular pyramid with the 

 apex pointing down. In dividing, a slice splits off from 

 one of the sides of the pyramid ; then a slice splits off 

 from a second side ; then one from the third side, the 

 pyramid growing to its original size before each nssion. 

 Each of the slices divides into many cells, which develop 

 into the tissues of the stem, leaves, and rhizoids. 



Mosses are reproduced asexually by different modes of 

 budding, but not, so far as is known, by asexual spores. 



