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wall. The upper half behaves quite differently. It 

 does not grow in length, but divides into two by a 

 vertical wall, and then each of these halves again 

 divides vertically, so as to form a inner cell, sur- 

 rounded by a ring of outer cells. This forms a 

 node of the stem, and from it the leaves are de- 

 veloped ; each from one of the outer circle of cells. 

 Lateral branches may also arise from the axils of the 

 leaves. 



The leaves repeat the development of the stem ; 

 but while in the stem the growth is unlimited, in 

 the leaves the growth is limited. After a definite 

 number of segments have been cut off, the apical 

 cell ceases to divide, and grows into a different shape 

 from the other cells of the leaf. The lateral 

 branches repeat the growth of the stem in every 

 respect. Eoot-like structures, called rhizoids 

 which are long tubes growing at the apex also arise 

 from the outer cells of the lower nodes. Each young 

 cell contains a nucleus in the centre, surrounded 

 with cytoplasm, which fills the rest of the cell ; and 

 in each bi-partition the nucleus- divides first. As the 

 cells of the internodes and of the leaves elongate, a 

 cavity, filled with sap, appears in the protoplasm;, 

 which then forms a thickish layer lining the cell 

 wall. A longitudinal rotatory movement com- 

 mences in the protoplasm. The outer layer, con- 

 taining the nucleus, is stationary, but the inner 

 portion moves ; the current being more rapid near 

 the outer stationary layer, and becoming gradually 

 slower towards the interior. These movements are 

 quite independent of gravitation or light, and are 



