]_78 MERRILL. 
Again, so far as the Philippines are concerned, 197 species are 
found only in cultivation, while 227 are spontaneous and more 
or less thoroughly naturalized. As to their origins, 177 have, for 
most part at least, originated in tropical America, and 138 in the 
tropical or subtropical parts of the Old World. In 109 cases it 
has been impossible to determine, with any degree of certainty, 
where they may have originated. 
In my consideration of the Manila flora I have assumed that 
about 550 species, considerably more than one-half of the total, 
are indigenous, that is, true natives of the Philippines, or plants 
that have reached the Archipelago by natural causes and without 
the direct aid of man. It must be admitted, however, if we 
assume as correct the theory that the original vegetation of the 
Archipelago was a practically unbroken forest, that very many 
of these species must have reached the Philippines since the 
advent of man. In contrast to the 550 species that are presum- 
ably indigenous, about 457 have certainly been introduced by 
man, either purposely or accidentally, some in prehistoric times, 
and others at more recent dates. A very considerable percentage 
of these introduced species must have reached the Archipelago in 
recent times, that is, since the Spanish conquest or after the year 
1521. Of the manifestly introduced species, about 225 are cul- 
tivated only, or at least spontaneous to but a small degree, and 
could not persist without the aid of man. 
Taking into consideration only those species included in my 
"Flora of Manila" I am of the opinion that my estimate of 457 
species introduced by man directly or indirectly, in the thousands 
of years that have elapsed since the group was first inhabited, is 
a very conservative one. For many centuries before the Euro- 
peans reached the East the commerce between the Philippines 
and surrounding countries was by no means inconsiderable. The 
early Spaniards found here Chinese, Japanese, and Indian mer- 
chants and traders, and there must from very early times have 
existed intercommunication between the Philippines and Malaya. 
Since the Spanish conquest, that is, in the 390 years that have 
elapsed since the Spaniards first came to the Archipelago, no less 
than 178 species, manifestly of American origin,, and over one- 
third of my estimated total of introduced forms, have been intro- 
duced into the Philippines, purposely or inadvertently, by man. 
More than 100 of these were brought to the Philippines between 
the years 1521 and 1815, for at the latter date regular communi- 
cation between the Philippines and the west coast of Mexico 
ceased. As the communication between the Philippines and 
