The Malay archipelago : the land of the orang-utan ... - Wallace Online

92 THE MALAY ARCHIPELAGO. [chap.though not identical with those of European mountains, belongto the same genera, and are said by botanists to represent them ;and most of these could not exist in the -warm intervening plains.Mr. Darwin believed that this class of facts can be explained inthe same way ;for, during the greatest severity of the glacialepoch, temperate forms of plants will have extended to the confinesof the tropics, and on its departure, will have retreated upthese .southern mountains, as well as northward to the plainsand hills of Europe. But in this case, the time elapsed, and thegreat change of conditions, have allowed many of these plants tobecome so "modified that we now consider them to be distinctspecies. A vai-iety of other facts of a similar nature, have ledhim to believe that the depression of temperature was at onetime sufiicient to allow a few north-temperate plants to crossthe Equator (by the most elevated routes) and to reach tlie Antarcticregions, where they are now found. The evidence onwhich this belief rests, will be found in the latter part ofChapter II. of the Or'ujin of Sj)ecies ; and, accepting it for thepresent as an hypothesis, it enables us to account for thepresence of a flora of European type on the volcanoes of Java.It will, however, naturally be objected that there is a wideexpanse of sea between Java and the continent, which wouldhave eftectually prevented the immigration of temperate formsof plants dui'ing the glacial ej^och. This would undoubtedly bea fatal objection, were there not abundant e\idence to showthat Java has been formerly connected vnth Asia, and that theunion must have occurred at about the epoch required. Themost striking proof of such a junction is, that the great Mammaliaof Java, the I'hiiioceros, the tiger, and the Banteng orwild ox, occur also in Siam and Burmah, and these wouldcertainly not have been introduced by man. The Javanesepeacock and several other birds are also common to these twocountries ; but, in the majority of cases, the species are distinct,thougli closely allied, indicating that a considerable time (requiredfor such modification) has elapsed since the separation,while it has not been so long as to cause an entire change. Nowthis exactly corresponds with the time we should require sincethe temperate forms of plants entered Java. These are almostall now distinct species ; but the changed conditions underwhich tliey are now forced to exist, and the probability of someof them liaving since died out on the continent of India,sufiiciently accounts for the Javanese species being difierent.^In my more special pursuits, I liad very little success uponthe mountain, o-s^ang, perhaps, to the excessively unpropitiousweather and the shortness of my staJ^ At from 7,000 to 8,000feet elevation, I obtained one of the most lovely of the smallfruit pigeons (Ptilonopus roseicollis), whose entire head and1 I have DOW arrived at another explanation of these and analogous facts, and onewhich seems to me more complete and less improbable. (See my Island Life, chap,xxiii., and Darwi7iism, pp. 362-373.)