PAST, PRESENT, AND FUTURE OF THE AUSTRALIAN FLORA. 139 



Australia. You will see from the paper that they have represen- 

 tatives from all the eontineuts of the globe ; aud some of these 

 migrated plants we can easily account for. We can account for 

 the large number of Asiatic species which have travelled down 

 the Mahiyan Archipelago, and for a number of the species of 

 N^ew Zealand and Polynesia, but when we come to j^frica, with 

 515 species common to Africa and Australia, and to 315 species 

 common to Australia and America (I presume South America), 

 the problem is evidently very much more difficult to solve. 

 But geology comes to our assistance here, because not only the 

 plant fauna, but the recent Tertiary fauua, of South America is 

 represented in Australia, and gives indication of a not very ancient 

 — indeed, a most recent — connection between South America 

 and Australia. Then with regard to the community of African 

 species, it is also known on geological grounds — on the comparison 

 of the former fauna of the two countries — that Southern Africa 

 was connected with Northern India by a tract of land which is 

 now under the Indian Ocean ; and therefore we can understand 

 how the plants migrated along this line into India, and then 

 southwards through the archipelago of islands down mto 

 Australia. All these questions are of extreme interest as showing 

 how very different is the distribution of land and sea, continent 

 and ocean, at the present time, in regard to their outline, from 

 what it was at a not very distant period of the world's history. 

 In this manner we can account, I think, for the remarkable fact 

 which is here stated, that Australia in its flora represents all the 

 continents of the globe. 



Surgeon-General Gordon. — There is one thing I should like to 

 remark upon, and that is the interest with which I have listened 

 to, and the great information I have derived from, some of the 

 remarks that have been made, more especially on the subject of 

 ii-rigation. It is within our own knowledge that, with regard to 

 the effect of vegetation and water mutually upon each other, only 

 a few years ago when the great Suez Canal was begun thei'e was 

 scarcely an atom of vegetation along- it, whereas now there is a 

 strip of vegetation springing up all along its banks. Of course the 

 matter that was mentioned with regard to the risk that there is, 

 and that the cii'cumstance had actually occui-red, of brackish water 

 having been got up from the lower reservoirs instead of fresh 

 water, simply confirms what I had previously heard, and it also 



