IX, C,1 Merrill: Plants of Guam 29 
theria. Guppy has effectively proved that it is quite impossible 
for the average weed seed, unaided, to be transmitted by ocean 
currents even for short distances. 
Seemann concluded that the reason why American weeds 
showed a greater tendency to become dominant in Polynesia than 
Asiatic ones was because to American weeds Polynesia is alto- 
gether virgin ground. In the first place I differ from him in 
that I consider the majority of the weeds enumerated to be of 
oriental, not American origin; and secondly, and what is of still 
greater importance, that if we assume the Polynesian islands 
originally to have been covered with continuous forests before the 
advent of man, then, as man has destroyed the forests, the islands, 
by the provision of proper habitats, would become just as much 
virgin territory to Asiatic as to American weeds. 
Whitford *' and myself '* have argued that for the Philippines 
the Islands were originally entirely covered with forests of one 
type or another before the advent of man. It is at once manifest 
that a country covered with continuous forests will present no 
habitats, or at least very limited areas, where the sun-loving 
weed flora can thrive or even persist. It is also manifest to 
any one familiar with the forests of the Malayan region that the 
vegetation of the forested areas is entirely different from that 
of the more or less open country, and that the weeds and weed- 
like plants that are dominant in the settled areas are normally 
absent in the forests; even in second-growth forests that are 
only a few years old. It is argued that the present vast ex- 
panses of territory in the Philippines, including the areas in 
cultivation, the second growth forest, and the enormous stretches 
of country that are covered with coarse grasses, primarily owe 
their existence to the presence of man, and that man, through 
destructive methods of clearing the ground for agricultural pur- 
poses, has provided the proper habitats for the weeds and weed- 
like plants, which, when once introduced, have spread with great 
rapidity and have become dominant in the open areas. The 
presence of the vast areas of grass-covered, unproductive lands 
in the Philippines, as well as the second-growth forests and the 
cultivated areas is certainly due to the continued presence of man. 
It is equally certain that if man were removed the country would 
eventually become reforested, and this would cause the entire or 
"The Forests of the Philippines. For. Bur. (Philip.) Bull. 10* (1911) 
12. 
” Notes on the Flora of Manila with Special Reference to the Introduced 
Element. Philip. Journ. Sci. 7 (1912) Bot. 148-151. 
