142 THE VEGETABLE KINGDOM. 



to have any distinct membranous wall, is filled with 

 granular particles of a green colour, and a ' nucleus ' 

 may sometimes be distinguished through the midst of 

 these. When treated with tincture of iodine, however, 

 the green contents of the cell are turned to a brownish 

 hue, and a dark-brown nucleus is distinctly shown. 

 Other cells are seen, which are considerably elongated, 

 some of them beginning to present a sort of hour-glass 

 contraction across the middle ; in these is commencing 

 that curious multiplication by duplicative subdivision 

 which is the mode in which increase nearly always 

 takes place throughout the vegetable kingdom." 



The higher tribes of Algae embrace the sea- weeds ; 

 these are for the most part broad, leaf-like expansions 

 of " thallus," composed of cellular tissue, they some- 

 times grow to an enormous length. Humboldt 

 mentions the sea-grass as extending for miles, and 

 forming continuous extensions of two or three hundred 

 feet, and the Macrocystis pyrifera attains to the length 

 of more than a thousand. The common Bladder- wrack 

 (Fucus vesiculosus) was formerly much used to procure 



Fucus Vesiculosus. 



soda from, its ashes containing a considerable quantity, 

 it is also used for manure ; the Laminaria digitata is 

 eaten under the name of " tangle," and a nutritious jelly 

 is made from the " Carigeen moss " (Glwndrus crispus). 



