Cockayne. — Botanical E.ratrsion to Southern Islands. 311 



South America, distant about half the circumference of the 

 globe ? Two explanations have been suggested : one that 

 seeds of these Fuegian plants were brought by winds, by 

 birds, by ocean currents, on icebergs, &c. ; the other chat 

 changes more or less great in the configuration of the lands 

 of the Southern Hemisphere have taken place, bringing dif- 

 ferent points eitlier into direct land-connnunication or very 

 much nearer than they are at present. Correlated with this 

 latter view is the belief that a milder climate may have existed 

 in the Southern Hemisphere than is now the case.* 



As to the first hypothesis, I may point out that introduced 

 land-birds have been blown from New Zealand to Auckland 

 Island and to Chatham Island, and that in consequence 

 certain European birds are now naturalised on these two 

 islands. The smoke of bush-fires reaches Chatham Island 

 during certain winds from New^ Zealand. Dr. P. iVIarshall 

 has recently shown (76) how a storm of dust has reached 

 New' Zealand from Australia, and how during such an occur- 

 rence small seeds could reach New Zealand from Australia. 

 Certain islands are supposed to have been colonised with 

 plants entirely by such methods as the above, the Azores 

 and Bermudas being cases in pomt. As for the latter group, 

 Trelease considers(lOl'i) that most of the existing species have 

 been introduced largely by human agency since the discovery 

 of the islands. 



As for the currents, Captain Bollons writes to me : "The 

 current, generally speaking, is a set to the eastward, some- 

 times at the rate of one and a half knots per hour. Have not 

 noticed anything m the shape of driftvvood or flotsam of any 

 kind which could be taken as coming from other lands." 

 So far as Chatham Island is concerned, logs from New Zea- 

 land have been frequently cast up on its shores. 



Sea-birds, as shown previously, are enormously abundant 

 on these islands. Some of these make their nests in the 

 ground, and so, as Moseley has shown, may get their feathers 

 covered with vegetable mould, which in some cases will con- 

 tain seeds. The fruits of Accsna, as shown above, adhere in 

 large numbers to the feathers of the albatros. Whether 

 such sea-birds visit anv other islands than the one on which 

 they breed I do not think is known ; nor are any facts available 

 as to how much exposure to salt-water the seeds of the plants 

 under consideration could tolerate. As to whether sea-birds 

 will eat the fruits of berry-bearing plants, for instance, there 

 is, so far as I know, only the testimony of Dr. Guppy (37), 

 which refers merely to one case. 



* This is now confirmed by Mr. Ferrar'e splendid discovery of fossil 

 plants on the Antarciic Contuieut, during the recent British Antarctic 

 Expedition. 



