182 IN THE GUIANA FOREST. 



some arrow-shaped leaves and waxy spathes like 

 great arum lilies. However the floating grass may 

 try to cover them with its dense mat they push 

 through the thickest covering. Each shoot is a 

 living spear, ready to pierce almost any accumu- 

 lation, and rise well above the surface before 

 opening its leaves to exclude the light from below. 

 Not only is it pointed, but also armed with thick 

 short thorns, which tear the leaves and stems of 

 everything the flood brings in its way. 



The great rivers of Guiana all contain islands of 

 different sizes, some as many as ten miles long, 

 and it may be confidently stated that nearly all 

 have been built up in this way by means of the 

 mocca-mocca, with the assistance of the host of 

 thorny Papilionacese. The banks of the rivers are 

 also kept up to a very great extent in the same 

 manner, and although high floods often carry away 

 great clumps of the arum, its recuperative power is 

 so great that the line is soon re-established. As the 

 river-banks or shores of the islands become con- 

 solidated the seeds of forest trees germinate, and 

 push through the low bushes until they can spread 

 their canopies of foliage over their more humble 

 rivals, and smother them ; then we get a bit of the 

 forest where once flowed the river. 



When we see such a grand work continually in 



