February 9, 1883.] 



SCIENCE. 



13 



its place in the list should be taken by the 

 cocoanut, the only esculent species common 

 to the two worlds within the tropics which we 

 have reason to suppose was carried or drifted 

 across the Pacific in prehistoric times. Being 

 a littoral tree, with fruit capable of enduring 

 long exposure to salt water, its dispersion is 

 not so surprising. The question is, in which 

 direction the dispersion was effected ; and that 

 perhaps can never be determined. In his 

 general list De CandoUe includes the Cocos 

 nucifera among the plants of old-world origin, 

 with queries whether of the Indian archipela- 

 go, or of Polynesia. In his former treatise he 

 inclined to the theory of a transmission west- 

 ward from the Pacific coast of Central Amer- 

 ica : in the body of the present work, after 

 full statements pro and con, he is disposed to 

 reverse his former opinion. But, as the disper- 

 sion may have been mainly by natural agen- 

 cies, the question ma}' be relegated to another 

 class of inquiries. The presumption arising 

 from the fact that all other species" of Cocos 

 are American, may be otfset by the asserted 

 fact that, although the tree formed forests on 

 the islands ofi' Panama when these were first 

 visited by Europeans, it would appear to have 

 only recently reached the West Indies and the 

 adjacent main. So useful a tree, if indigenous 

 to one side of the isthmus, would have been 

 transported to the other and to the islands be- 

 yond by the very earliest races of men. As 

 to oceanic transport, judging from the charts, 

 the drifting of cocoanuts from America to 

 Polj'nesia by the great current south of the 

 equator seems hardly more or less likely than 

 the reverse by the return equatorial current 

 north of it. 



It would be well to give some account of 

 our author's method of investigation and 

 exposition, of the kinds of evidence which are 

 brought to bear upon the questions discussed, 

 botanical, paleontological and archeological, 

 historical and linguistic, each bringing some 

 light of its own sort, and in their coincidence 

 giving all the assurance of which such inqui- 

 ries admit. It would be interesting to show, 

 moreover, that although in most cases the 

 continent or even the country fi'om which each 

 plant came to Europe, or in which it has been 

 immemorially cultivated,- has been fairly well 

 ascertained, their origin or parentage has not. 

 Only one-third of them are really known 

 to botanists in a natural or wild state ; and 

 from this number subtraction maj- be made of 

 such as have been detected only once or twice, 

 and which maj' merely have run wild : the 

 common tobacco-plant of the new world, and 



the bean of the old, are in this category. On 

 the other hand, there are several which botan- 

 ists confidently trace to indigenous originals 

 from which the cultivated plant has undergone 

 considerable alteration : of such are the olive, 

 the vine of the old world, flax, and the gar- 

 den popp3' ; and in America, the potato, the 

 sunflower-artichoke, and the tomato. But we 

 know not, and we probablj' shall never dis- 

 cover, the particular source or origin of the 

 cereal grains of the old world, and of maize 

 in the new ; of sorghum and sugar-cane ; of 

 the pea, lentil, chick-pea, and peanut, and 

 of the common white bean ; of sweet-potato 

 and yams ; and nearlj' the same may be said 

 of the peach, oranges and lemons, and of all 

 squashes and pumpkins. 



But we must conclude our brief review 

 with a note upon two or three plants, the early 

 history of which concerns our own country. 



Phaseolus vulgaris, our common bean, * 

 ranks in De Candolle's table as one of tlie 

 three esculent plants, the home of which, even 

 as to continent, is completely unknown. Lin- , 

 n6 credited it to India, as he did our Lima 

 bean also ; but he took no pains to investigate 

 such questions. This has been so generallj' 

 followed in the books, that even the Flora 

 of .British India in 1879 admits the species, 

 adding that it is not anj'where clearly known 

 as a wild plant. But Alph. De Candolle, in 

 his former work, had discarded this view, on 

 the ground that it had no Sanscrit name, and 

 that there was no evidence of its early culti- 

 vation in India or farther East. Adhering, 

 however, to the idea that our plant was the 

 Dolichos and the Phaseolus or Phaselos of the 

 Greeks, and of the Romans in the time of 

 the Empire, he conjectured that its probable 

 home was in some part of north-western Asia. 

 But recently, as "no one would have dreamed 

 of looking for its origin in the new world," 

 he was greatly surprised when its fruits and 

 seeds were found to abound in the tombs of 

 the old Peruvians at Ancon, accompanied b}' 

 many other grains or vegetable products, 

 ever}' one of them exclusivelj' American. In 

 his present very careful article he admits that 

 we cannot be sure that it was known in Europe 

 before the discovery of America, and that 

 directly afterwards many varieties of it ap- 

 peared all at once in the gardens, and the au- 

 thors of the time began to speak of them ; that 

 most of the related species of the genus belong 

 to South Amei'ica, where, moreover, man}' 

 sorts of beans were in cultivation before the 



