LTXXEAX SOCIETY OF LONDON. 8l 



4. The Scandinavian plants growing on the sumurits of our 

 rnonntains and in an increasing number as we proceed north- 

 wards. 5. The plants of Central and Western Europe which 

 made up the general Flora of the British Isles. 



In investigating this important question of their transport to 

 our islands, he concluded that the great mass of our Flora had 

 migrated from the continent after tlic bed of the glacial sea had 

 been elevated to form a land-passage to England. The ai'rival 

 of the Scandinavian contingent was, ho considered, much earlier, 

 because the areas of their growth had become isolated on moun- 

 tain-ranges before the appearance of the Central-European 

 plants. So he conceived that daring a part of the Grlacial 

 Period the land was submerged under the sea, until the higher 

 mountains appeared as scattered islands, when they were taken 

 possession of by the Northern plants. 



The French Floras in Kent and Devon must have reached our 

 shores over a tract of laud now destroyed, probably before the 

 advent of the great bulk of our Flora from Grermany. And 

 lastly the Peninsular species at a still earlier period reached 

 Ireland by a tract of laud which stretched across the Bay of 

 Biscay ; and of these plants only the hardy representatives 

 remained througli the climatal vicissitudes to our day. 



Charles Darwin in his 'Origin of Species' investigated the 

 means by which Oceanic Islands were peopled with plants, and 

 concluded that the different species reached thetn without the 

 aid of intervening laud. Seeds were floated by ocean-currents, 

 spores and minute seeds were borne by winds, and others were 

 carried by birds, either passing through their intestinal canal 

 without digestion or being attached to their feet or their 

 feathers. 



Sir J. D. Hooker, while admitting the force of Darwin's array 

 of facts and argumeuts, is yet unwilling to give up land connec- 

 tion witli continents in the past as an efficient means of trans- 

 porting seeds to islands. 



Mr. Hemsley has more recently made Insular Floras a special 

 study, and wliile he looks upon a Southern Continent connecting 

 America, Africa, and Australia as the solution of the problems 

 in connection with the distribution of plant-life in the Oceanic 

 Islands of the Southern Ocean as well as on the great Southern 

 Continents, he j^et demonstrates hj the investigation of many 

 island floras the influence of ocean currents and of birds in tlie 

 transport of the elements of their floras. Dealing with the Flora 

 of Bermuda, which he critically investigated in counectiou with his 

 Avork on the collections of the ' Challenger' Expedition, he thus 

 classifies the plants according to the means by which they reached 

 the islands : — 45 species, chiefl}' littoral plants, conveyed by 

 ocean currents, 2 marsh plants, introduced by their small seedis 

 adhering with mud to the feet of birds ; he thinks it, however, 

 more probable that many of these two grouj^s may have come m 



LTTSTN. SOC. PH0CKP:DTN(JS. — SESSION lS,S9-9(). g 



