DIFFERING AUTHORITIES. 215 
of species is largely a matter of the crossing of little species with 
one another. 
The preceding portion of this chapter, as also Chapter X, has 
shown what a varied flora occupies New Zealand, and how diverse is 
its origm. Now comes the question, How has this wonderful assem- 
blage been enabled to reach and occupy a group of islands surrounded 
by a vast stretch of ocean? To ask the question is easy enough, but 
a satisfactory reply is one of great difficulty. As seen from. what 
was said at the beginning of this chapter, data not available at 
present are urgently needed. To answer the question imagination 
and conjecture must come into play together with such geological 
evidence and biological statistics as have been given, and a con- 
sideration of means of transit of seeds and spores across hundreds 
or it may be thousands of miles of landless ocean. Here, too, the 
opinion of one man is of much less moment than that of the many 
who have given consideration to this difficult subject. Unfortu- 
nately, there is no uniformity of opinion. The authorities on plant 
and animal distribution are divided into two opposite schools, the 
one denying the possibility of long-distance transit, and invoking 
great changes in the land and ocean areas; while the other believes 
in the comparative permanence of oceans and continents, and in 
the likelihood of certain classes of animals and plants being con- 
veyed to almost any distance by winds, birds, floating logs, and 
so on. This latter school generally neglects the question as to the 
possibility of establishment of an organism even if its seeds or 
spores arrive intact after long travel, but it assumes that during 
unthinkable periods of time there must be sufficient arrivals for 
successful colonization. 
Taking the case of New Zealand, the consensus of opinion is that 
there has been once or twice land connection with Malaya, and here 
may be suggested also an early connection with Australia. It is over 
the South American or the Antarctic connection that the biological 
battle is waged, for the ocean between New Zealand and Antarctica is, 
‘from a little to the south of Campbell Island almost to the Antarctic 
Circle, perhaps up to 9,000 feet deep. However, the zoological 
evidence, thanks in part to the researches of Hutton, Benham, 
and Chilton in this country, is so strongly in favour of a former 
“land bridge’—evidence not based on a few isolated cases, but on 
the distribution of whole groups of the lower animals—that the . 
