CoLGAN — Tropical Drift Srr(h on Jrif/i Afhtv/tc Coasts. 43 



of natural trail sport, I may cite Gumiar Aiidcrseii, the wcll-liiiowii investigalor 

 of the early botanical history of Scandinavia, who in 1893 recorded the finding 

 of the Entada bean in two distinct stations in tlic jjoat-bogs ol' 'i'j(ii n, an island 

 which lies off the coast of the Skager-Eack in the Sv/odish Ian or county u( 

 Bohus.i From the nature of these peat deposits and their comparatively 

 small elevation above sea-level, he considers it probable that the beans had 

 been carried thither at a time previous to the post-glacial subsidence in tliat 

 region ; and in subsequent papers he found in the occurrence of these tropical 

 waifs proof that a branch of a warm ocean current had washed the coast of 

 southern Sweden in the period known to geologists as the Littorina Age.- 

 Whatever date may be assigned, in accordance with this view, to the deposi- 

 tion of these seeds in the peat of Tjorn Island, we may safely assume that it was 

 long anterior to any trade intercourse between Scandinavia and the Tropics.'' 



The evidence in support of each of the two conflicting views as to the 

 method of transport has now been set fortli at full length ; and few, I think, 

 who weigh it will hesitate to give a verdict in favour of the natural method, 

 of that co-operation of current, drift, and wind commonly, though, it would 

 seem loosely and inaccurately, spoken of as the Gulf Stream. For those who 

 accept as sufficient the alternative method of transport by human agency plus 

 shipwreck the occurrence of tropical seeds on Irish sea beaches must remain 

 a matter of indifference, since the interest which attaches to these ocean 

 waifs is inseparable from the belief that they traverse vast ocean spaces, 

 impelled by natural forces whose nature and origin still remain largely 

 mysterious. The evidence available appears to show that the agencies whicli 

 effect this transport are not all of them persistent or subject to regular 

 periodicity. The latter stage of the transit from mid-Atlantic, where the 

 permanent Gulf Stream ceases to act, to the shores of west Ireland, or, at all 

 events, a portion of that latter stage, is probably effected by irregularly 

 recurrent spells of westerly or south-westerly winds, since the finding of the 

 seeds on our Atlantic beaches occurs at irregular intervals. 



It may be asked at what rate the passage of these waifs is effected from 

 the West Indies or from the estuaries of the Amazon or Orinoco, whence not 

 improbably some of them are derived via the Gulf of Mexico. Dr. Guppy has 

 collected and discussed a large body of evidence on this point afforded by the 

 behaviour of numerous experimental battles and floats droppeil overboard at 



' " Viixtpaleontologiska uiKlersoIoHiigiir .if Svenska torfmoasar." Biliang Svensk. 

 Vefc. Akad. Haiidl. Bd. 18 Afd. iii, No. S, .sid. 40, lcSri3. 



2 "Svenska V.^xtvevldeiis Hisloria." Bot. .Jahrliuchor. Bd. 22, j). 474, 1897. 



3 " Die Veranderungoii des Kliiiias seit dem Ma.xiimim der lotzton Eiszoit." Iiitcrnat. 

 Geol. Kongress, Stockholm, 1!)10, p. 293. 



