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MERRILL. 
natural agencies, and that 457 have purposely or inadvertently 
been introduced by man. Of the introduced species somewhat 
over one-half, or 232, are spontaneous, while about 225 are 
never or but very rarely met with outside of cultivation. One 
hundred and seventy-eight of these introduced forms are con- 
sidered to have originated in tropical America, the remainder 
for the most part in the tropical parts of the Old World. Four 
hundred and twenty-five species are found in the tropics of both 
hemispheres, but less than 90 of these are considered as being 
possible or probable natives of both; 334 are considered as 
having been manifestly distributed by man, and chiefly within 
historical times. Of the total of 1,007 species found in and about 
Manila 812 extend to the Malay Archipelago, 789 to tropical 
Asia, 425 to tropical Australia, 355 to Polynesia, and 402 to 
tropical Africa. 
Table I . — Summary of the families, genera, and species, found in and 
about Manila, with indications of the origin and range of the various 
forms. 
