14 Transactions. — Miscellaneous. 



nesia the cocoauut was of the utmost importance, as many of 

 the islands would have been uninhabitable without it. If its 

 presence on these islands was due to cultivation, we have in it 

 another important evidence of the colonisation of the region. 



Yam (Dioscorea alata). — The numerous species of the genus 

 Dioscorea are scattered over the tropical portions of the Old 

 and New Worlds. Many have large farinaceous rhizomes, 

 which differ much in quality, some being good for human food, 

 others having acrid or even poisonous properties. Yams, as 

 these rhizomes are generally termed, have been used as food 

 by the rude inhabitants of all tropical countries wherein they 

 are found before they became acquainted with the art of 

 agriculture. 



Baron von Mueller informs us that the aborigines of Aus- 

 tralia consume large quantities of the roots of Dioscorea hasti- 

 folia, and that "it is the only plant on which they bestow 

 any cultivation, crude as it is.""' Probably the yam was one 

 of the first roots cultivated by man. In the New World 

 several species were found in cultivation by the early Euro- 

 pean explorers ; none of these exactly agreed with Old- World 

 species, but some of those found on the western side of the 

 continent were allied to Japanese forms. 



The common yam {Dioscorea alata) was found in cultiva- 

 tion throughout Polynesia by the old European navigators. 

 Another species, Dioscorea saliva, was also cultivated, but the 

 rhizomes contained an acrid principle, and required a particular 

 sort of cooking, hence it was less in vogue thanD. alata, which 

 seems to be foreign to the region, though its original habitat 

 cannot be accurately determined, it being now very widely 

 spread both on the mainland and the Asiatic islands. Since 

 the European discovery of America the indigenous species 

 cultivated there have been superseded by African and Asiatic 

 species. 



This process of selection, when the cultivated plants of 

 difi"erent regions become intermingled, is seen in the case of 

 Triticiim spelta, which is now only found in a few places in 

 South Germany and Switzerland, having been driven out of 

 cultivation by wheat [TritictLm vulgare). As the spelt has not 

 been discovered wild, ic will probably become extinct should 

 it cease to be cultivated. We may thus see that plants 

 brought into cultivation at a very early period may have been 

 subsequently lost through the invasion of their territory by 

 species better fitted to supply the wants of the inhabitants. 

 How readily a rude agricultural people adopt new plants that 

 can be advantageously grovv'n by them is seen in Africa, where 

 the manioc, maize, and sw^eet potato, all New-World species, 



' " Select Extra- tropical Plants." Baron F. von Mueller. 



