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Show I 49G ISLAND LIFE. (rAU'l' JI. greater hardiness of the former, from having been developed in a colder region, and one where alpine and arctic conditions extensively prevail; whereas the southern floras have been mainly developed in mild regions to which they have been altogether confined. While the northern plants have been driven north or south by each succeeding change of climate, the southern species have undergone comparatively slight changes of this nature, owing to the areas they occupy being unconnected with the ice-bearing Antarctic continent. It follows, that whereas the northern plants find in all these southern lands a milder and more equable climate than that to which they have been accustomed, and are thus often able to grow and flourish even more vigorously than in their native land, the southern plants would find in almost every part of Europe, North America or Northern Asia, a more severe and less equable climate, with winters that usually prove fatal to them even under cultivation. These causes, taken separately, are very powerful, but when combined they must, I think, be held to be amply sufficient to explain why examples of the typical southern vegetation are almost unknown in the north temperate zone, while a very few of them have extended so far as the northern tropic. 1 Ooncl·uding remarks on the last two chapters. -Our inquiry into the external relations and probable origin of the fauna and flora of New Zealand, has thus led us on to a general 1 The fact stated in the last edition of the 01'igin of Species (p. 340) on the authority of Sir Joseph Hooker, that Australian plants are rapidly sowing themselves and becoming naturalised on the Neilgherrie mountains in ihe southern part of the Indian Peninsula, though an exception to the rule of the inability of Australian plants to become naturalised in the Northern Hemisphere, is yet quite in harmony with the hypothesis here advocated. For not only is the climate of the N eilgherries more favourable to Australian plants than any part of the North Temperate zone, but the entire Indian Peninsula has existed for unknown ages as an island and thus possesses the "insular" characteristic of a comparatively poor and less developed flora and fauna as compared with the truly " continental" Malayan and Himalayan region~. Australian plants are thus enabled to compete with those of the Indian Peninsula highlands with a fair chance of success. CHAr. xxm.] AHCTIC pLANTS IN NEW ZEALAND. ~=-~~----------~~==::~----~497 ttwheeoerny atsh et o thteh ca use of t h e pecuh. ar bw. logical relations be-better or mn or ern. and the sou th ern h emi. spheres ; and no rancre and ore tty?Ical example could be found of the wicle o grca mtcrest of th t d f distribution of anim 1 d 1 e s u Y 0 the geographical . as an pants. The solu.hon which has here b . difficult of this l f con given of one of the most solely by the kn::~s cl~ problems, has bc~n rendered possible the e -b tt . e be very recently obtamcd of tho form of strucst uar e oo f omth em the southe.r n . oc ean, an d of the geological k l d great Australian continent. Without th. now e gc we should have noth. b t . IS probabilities on which to £ dng uh a sen:s of guesses or which we have no b bolun our ypothetical explanation, w een a e to build I'd .c of fact. The com I . up on a so 1 10undation durincr the C t p ete sep.aratwn of East from West Australia o re aceous penod ld h till it was established by th colu b ~ever ave been guessed A t l' e a onous explorations of th us ra Ian geologists; while the h th · f . 0 shallow sea, uniting New Zealand ypo esis o a cor:nparatively Australia, while a profoundly d by a long ~outo With tropical from temperate A~stralia, woul~ep h:~=a~e::ays. setpadrated it improbabl · · reJCC e as too . . e a suppositiOn for the foundation of oven th t ehntitcmg theory. byl et it is mainly by means of these tw~ f:c~:t a we are en.a e.d to gi ve an a d equate explanation of the' t shtratngef aNnomahes m the flora of Australia and its relation to a o ew Zealand. I.n the more general explanation of the relations of the v· anous nort. hern and southern floras ' I h ave sh own what an Imh portant fa id1 ' to any such explanation is the th eory of repeated c anges o c Imate, not necessarily of great amount . . . hth Ch . ' given m ?ur elg apter; while the whole discussion justifies the Imf portta. nce t attacdh ed to the theory of the g en era1 permanence o. con men ~ an oceans, as demonstrated in Chapter VI smce any rational explanation based upon facts ( d ., -l • as oppose to mere unsupporteu conJecture) must take such general t . . perma-nence as a s artmg-pomt. The whole inquiry into the h me . t d b · 1 p eno~ na presen e y IS ands, which forms the main subject of th present volume has, I think, shown that this theory does affor~ KK |
