VOLCANIC ERUPTIONS 



But the turn of the moss is coming. Here a few grass- 

 blades, there a tiny plant of Sandwort, possibly a Rock Bed- 

 straw, begin to root themselves in the moss. 



If people would only let the wall alone, it would soon be 

 festooned with hanging plants, and producing quantities of 

 grass, but somebody is sure to find that it looks very untidy, 

 and everything is torn off the wall, which again looks new 

 and raw and clean. Then of course the pioneer lichens begin 

 again ! 



Some very interesting and remarkable facts have been dis- 

 covered about the way in which lavas and basalts have been 

 occupied by the plant world. 



In the great volcanic eruption of 1883, the whole island of 

 Krakatoa was covered by hot lava and glowing ashes. In 

 1884 and 1885 the sunsets were remarkable for a curious 

 fiery red or orange glow, which was popularly supposed to be 

 due to the volcanic dust of that explosion. It is said 

 that the dust travelled three times round the earth, though 

 I do not know on what authority. 



However, on Krakatoa island there was left a clean "slate." 

 There were neither bacteria, nor leaf-mould, nor living plants 

 of any kind ; no spores or seeds could have endured the fiery 

 furnace of the eruption. 



Three years afterwards the botanist Treub visited the 

 island. He found that the rocks had been first covered by 

 thin layers of minute freshwater Algae, but that ferns were 

 then occupying and inhabiting the lavas. Eleven kinds of 

 ferns, and but very few other plants, were discovered. 



People were interested in this, and Dr. A. F. W. Schimper 

 then visited another volcano which had been pouring out 

 huge streams of lava in 1843. He found that there were 

 still plenty of ferns, but also numbers of shrubs and other 



171 



