LIFE IN PRIMARY PERIOD 241 



Lepidodendrons — a vegetation typical of damp soils. 

 Abundant water, in fact, was essential to the fecundation of 

 these plants, as their antherozoids could move only in drops 

 of rain or dew. The place they occupied in relation to the 

 higher plants might be compared with that of the Batrachians 

 in relation to the land Vertebrates. They were ill adapted 

 to grow on mountain slopes. However, tachygenesis gradually 

 suppressed their complicated method of reproduction ; the 

 microspores became pollen grains l and acquired the power of 

 fertilization ; thus the wind sufficed to carry them to the 

 ovules. Thenceforward the Cordates were enabled to cover 

 the ground with a forest of reeds, and Conifers were enabled 

 to climb the mountain-sides, whilst Cycads spread out their great 

 plumes in the sheltered valleys to be borne away on the wings of 

 the tempests. Wherever roots could penetrate the soil became 

 clothed with a vegetation that was extraordinarily luxuriant 

 in Carboniferous times, but so fragile that the wind often 

 stripped its branches, broke its stems, and tore the plants 

 up by the roots. The remains of such as grew in marshy 

 regions or along the borders of lakes have accumulated in situ. 

 Protected by drift brought down by floods, or by the mud 

 spread over them by the waters, these beds of fallen vegetation 

 have been preserved to us. Plants that grew on the valley- 

 slopes, far from the sea, as in the Central Plateau, were carried 

 along by torrents to the freshwater lakes, which they gradually 

 choked up. We can still identify the successive layers thus 

 formed by floods at the height of each inundation. Still others 

 were carried as debris by the great rivers down to the sea, as the 

 Mississippi still carries it at the present day. And as this 

 went on through century after century, in the course of 

 which the configuration of the earth scarcely changed and the 

 rivers kept to their old beds, vast accumulations of trunks, 

 branches, leaves, and even herbs formed, thus creating the 

 coal seams which feed our modern industries. 



But while all this preparation for the mad activity that 

 devours us to-day was slowly taking place, nature itself was 

 silent and stern. Not a single flower lightened with the fresh 

 colours of its petals the sombre green monotony, scarcely even 

 varied in shade, of the vegetation, for, as there were no seasons, 



1 p. 101. 



