LIVERWORTS AND MOSSES. 



45 



(2) The large-celled colorless tissue forming the lower half of section ; 

 the sections oi " leaves " arising near midrib and concave towards center. 



54. The shoot. — In the greater number of liverworts the 

 mature vegetative body is a shoot, which is differentiated 

 into stem and leaves (figs. 40, 41). Even in such a body 

 the dorsiventral character is well 

 marked. The stem is slender 

 and bears three (rarely more 

 or fewer) rows of leaves, of which 

 the two dorsal rows are the larger. 



Fig. 40. Fig. 41. 



Fig. 40. — Gametophyte of Bazsnnia Nova-HollandieE. Besides the ordinary branches 



there are slender ones (tlagella) with sparse minute leaves. Natural size. — After 



Lindenberg and Gottsche. 

 Fig. 41. — .4, dorsal view; 5, ventral view of a piece of fig. 40, magnified about 12 



diam., showing the stem, bearing two dorsal rows of large leaves and one ventral 



row of small ones. — After Lindenberg and Gottsche. 



while the under leaves are much smaller, even to being incon- 

 spicuous or wanting. These leaves consist of a single sheet 

 of uniform cells richly supplied with chloroplasts, as are also 

 the outer cells of the stem. Their form is very varied and 

 often of great beauty. They are usually crowded so closely 

 as to overlap each other more or less, and hide the stem 

 completely (fig. 41). 



