132 STRUCTURAL BOTANY 



slender indeed in comparison with the main filaments. 

 The whole simulates a regular root system, though 

 totally different in structure. 



b. Apical Development 



The stem of all Mosses grows by means of a single 

 apical cell, and the plant is built up in the most 

 regular manner from its segments. The cell is of the 

 same inverted pyramidal form which we found in 

 Equisetum, and divides at first in the same way by 

 walls parallel (or nearly parallel) to the three sides. 

 Each segment first divides into an inner and an outer 

 cell. From the inner cells thus formed the greater 

 part of the tissues of the stem is derived, while the 

 outer cells give rise to leaves, buds, and the outside 

 part of the stem. Each outer cell divides into an 

 upper and a lower half ; from the upper half the leaf 

 is produced, while the lateral buds, where they exist, 

 owe their origin to the lower of the two cells. We 

 see then that every segment produces a leaf, and that 

 each lateral bud stands below the leaf to which it 

 belongs, instead of in its axil, a striking difference 

 from the higher plants, though we find something like 

 it among the Ferns. Each leaf grows in length by 

 means of a two-sided apical cell. The chief points 

 then in the development of a Moss stem are the growth 

 from an apical cell, the origin of a leaf from eacli 

 segment, and the position of the lateral buds beneath 

 the leaves to which they belong. 



2. THE SEXUAL ORGANS' 

 Funaria is dkecious, though this is not the case 



