BOTANICAL BIOLOGY. 405 



bioloj2:ists of all countries must owe to Messrs. Godniaij and Salvin wlieii 

 llieir iuduons undertaking' is conii»leted. 1 am happy to say that the 

 botanical portion, which has been elaborated at Kew, is all but finished. 



In South America, I must content myself with referring to the great 

 "Flora Brasiliensis," commenced by Martins half a century ago, and 

 still slowly i)rogressing under the editorship of Professor Urban, at 

 Berlin. Little discussion has yet been attempted of the mass of material 

 which is enshrined in the mighty array of volumes already published. 

 But the travels of Mr. Ball in South America have led him to the 

 detection of some very interesting i)roblems. The enormous pluvial 

 denudation of the ancient portions of the continent has led to the 

 gradual blending of the flora of different levels with sufficient slowness 

 to i)ermit of adaptive changes in the process. The tropical flora of 

 Brazil therefore presents an admixture of modified temperate types 

 which gives to the whole a peculiar character not met with to the same 

 degree in the tropics of the Old World. On the other haml, the com- 

 paratively recent elevation of the southern portion of the continent 

 accounts in Mr. Ball's eyes for the singular poverty of its flora, which 

 we may regard indeed as still in progress of development. 



The botany of the Ghallenger expedition, which was also elaborated 

 at Kew, brought for the first time into one view all the available facts 

 as to the floras of the older oceanic islands. To this was added a dis- 

 cussion of the origin of the more recent floras of the islands of the 

 Western Pacific, based upon material carefully collected by Professor 

 Moseley, and supplemented by the notes and specimens accumulated 

 with much judgment by Dr. Guppy. For the first time we were enabled 

 to get some idea how a tropical island was furnished with plants, and 

 to discriminate the littoral element due to the action of oceanic currents 

 from the interior forest almost wholly due to frugivorous birds. The 

 recent examination of Christmas Island by the English Admiralty has 

 shown the process of island flora-making in another stage. The plants 

 collected by Mr. Lister prove, as might be expected, to be closely allied 

 to those of Java. But the effect of isolation has begun to tell ; and I 

 learn from my colleague, Professor Oliver, that the plants from Christ- 

 mas Island can not be for the most part exactly matched with their 

 congeners from Java, but yet do notdirter sufficiently to be specifically 

 distinguished. We have here therefore it appears to me, a manifest 

 <!ase of nascent species. 



The central problem of systematic botany I have not as yet touched 

 ui)on: this is to perfect a natural classification. Such a classification, 

 to be i)erfect, must be the ultimate generalization of every scrap of 

 knowledge which we can bring to bear uj)on the study of plant affinity. 

 In the higher i)lants, experience 'has shown that we can obtain results 

 which are sufficiently accurate for the i)resent, without carrying our 

 strncjtural analysis very far. Yet even here, the correct relations of the 

 Gymuosperms would never have been ascertained without patient and 



