654 



HUTCHINSON'S POPULAR BOTANY 



Chara invested by a cortex consisting of long slender cells arranged spir- 

 ally, but in Nitdla there is no such cortex, and 

 the internodal cell stands absolutely naked. 

 Chara also extracts calcium carbonate from the 

 water, and deposits it on its exterior to such an 

 extent that it is often difficult to make out the 

 structure through it. Nitdla has no such de- 

 posit. Long tubular cells grow downwards and 

 serve as roots to fix the plant in the soil. In 

 the clear internodal cells of these plants may 

 be observed the phenomenon known as cyclosis, 

 or rotation of the protoplasm along well-defined 

 routes up one side of the cell and down the 

 other, the two currents being separated by clear 

 bands devoid of chlorophyll. In the axils of the 

 leaves will be seen two kinds of bodies, some 

 round and orange-red, the others elliptical and 

 apparently green. The red bodies are antherids, 

 the green are oogones. These oogones under the 

 microscope are really orange, but the colour 

 being masked by surrounding green bracteoles, 

 they appear green to the naked eye. Some 

 plants produce organs of one kind only ; in 

 others the two kinds are found close together. 

 Each of these organs is supported on a short 

 stalk consisting of the pedicel-cell (fig. 698). 



The walls of the antherid are composed of 

 eight flat cells, and from the centre of each on 

 the inner surface a cylindrical cell the manu- 

 brium is attached, and extends towards the 

 centre of the antherid, where it supports a 

 rounded cell, the capituium. Each capitulum in 

 turn supports six secondary capitula of smaller 

 size, and each of these bears four coiled fila- 

 ments, which are divided into a large number of 

 flat cells, and in each of these is a spirally coiled 

 antherozoid, like those of the Mosses, with a 

 couple of long cilia at the anterior extremity. 

 When these are ripe, the antherid falls apart and 

 the antherozoids move through the water by 

 lashing their cilia. The red colour is due to 

 the inner face of the wall-cells being lined with 

 chlorophyll-grains, which turn red as the antherid 

 develops. 



FIG. 701. SUGAK TANGLE 

 (Laminaria saccharina), 



With root-like suckers holding to a 

 piece of rock. 



