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introduced into a garden from Australia. They all sank in a few 

 days, and on being cut across the seed displayed but little un- 

 occupied space in its cavity. I have no doubt that the Pacific 

 form of this plant has been at times dispersed by the currents, not, 

 however, through the fruits, but through the seeds. It is also quite 

 possible that it may have been introduced by a pre-Polynesian 

 people into the Pacific. 



Summary of the Chapter 



(1) Man in his distribution over the Pacific islands reproduces, 

 but in a less degree, nearly all the difficulties presented by the 

 plant in its dispersal. In both we have the age of general 

 dispersion followed by a suspension more or less complete of the 

 migrating movements ; and in both we have differentiation 

 associated with the isolation. 



(2) The Pacific islanders possess two sets of food-plants. In 

 addition to those commonly cultivated in our own time, such as 

 the yam, the taro, the banana, &c., there are a number of food- 

 plants now growing wild, but rarely cultivated, and only used when 

 the others fail. These plants, which include the wild yams, the 

 mountain bananas, Tacca pinnatifida, Pandanus odoratissimus, and 

 several others, are regarded as older than the Polynesians in the 

 Pacific, and as having probably formed the food of a pre- 

 Polynesian race that practised only a rude sort of cultivation. 



(3) The weeds of Polynesia also fall into two groups. In 

 the first place there are the aboriginal weeds, of which those found 

 in this region by Captain Cook's botanists in the latter part of the 

 1 8th century are taken as examples. These include species of 

 Urena and Sida, besides Waltheria americana, Oxalis corniculata, 

 Bidens pilosa, and many other weeds. In the second place, there 

 are the numerous weeds that are known to have been introduced 

 by the white man since the voyages of the English and French 

 navigators of Captain Cook's time. 



(4) There is reason to believe that many weeds now cosmo- 

 politan in the tropics had obtained their present distribution in 

 America and in the Old World before the Polynesians entered the 

 Pacific. It is thus that we can explain how there existed in these 

 islands at the time of their discovery by Cook, Bougainville, and 

 other navigators of that period, a number of weeds that have their 

 homes in America. 



