EXPLANATION OF JOGGINS SECTION. 



195 



mites grew on wet mud and sand-flats, and also in swamps ; and they 

 appear to have been especially adapted to take root in and clothe and 

 mat together soft sludgy material recently deposited or in process of 

 deposition. When the seed or spore of a Calamite had taken root 

 (and it is not unlikely that, like the very remarkable spores of the 

 Equiseta, their seeds had wings which expanded to waft them through 

 the air when dry, and closed instantly when they touched the damp 

 soil), it probably pi'oduced a little low whorl of leaves surrounding 

 one small joint, from which anotlier and another, widening in size, 

 arose, producing a cylindrical stem, tapering to a point at the base. 

 To strengthen the unstable base, the lower joints, especially if the 

 mud had been accumulating around the plant, shot out long roots 

 instead of leaves, while secondary steins grew out of the sides at the 

 surface of the soil, and in time there was a stool of Calamites, with 

 tufts of long roots stretching downwards, like an immense brush, into 

 the mud (Fig. 37. See also Fig. 39). When Calamites thus grew 



Fig. 39. — Erect Calamites [0. Suchovii), showing the Mode of Growth of New Stems, 



and Forms of the Ribs. 



f»T® 



iC) 



(a) 



Natural size. Half natural size, 



(a) Old stem, (h) Second stem, budding from first, (c) Third stem, budding from second. 



on inundated flats, they would, by causing the water to stagnate, 

 promote the elevation of the surface by new deposits, so that their 

 stems gradually became buried ; but this only favoured their growth, 

 for they continually pu.shed out new stems, while the old buried ones 

 shot out bunches of roots instead of regular whorls of leaves. These 

 peculiarities have caused much dispute among botanists, some of wliom 

 have even fancied that the whole stem served as a root. All the 



