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species. It occupies the eastern slopes of the hills almost com- 

 pletely, extends just to the ridge at the very top, and there 

 meets the forest with a very sharp tension line. The margin 

 of the forest is so abrupt that it looks like a solid vertical wall 

 or hedge, and it follows the sharp ridge of the hill so closely 

 that a single step into the forest may be a step of a foot or two 

 downward as well. In one or two places here, where small de- 

 pressions extend across the crest and into ravines on the east, 

 or cogon side, Bauhinia malaharica has established itself. The 

 trees are low, widely branched, with rounded spreading crowns, 



Fig. 7. Road through a coconut orchard, PhiHppine Islands. 



and look very much like the American black-jack oak, Quercus 

 marilandica. Under them is very little underbrush, so that one 

 walks through the forest about as easily as through a dense 

 forest of second-growth in America. In fact, the Bauhinia 

 forest here bears the same relation to the cogon association 

 that the black-jack and black oak forest bear to the prairies in 

 Illinois. In each case the rapid advance of the forest is pre- 

 vented by fires, while these trees, because of their fire-resisting 

 qualities, are the pioneer species in the advance. It is also 

 probable, although we did not observe it, that this pioneer 

 forest, like its analog in Illinois, is in turn succeeded by another 

 forest of more mesophytic type. 



