Willis . — Plant Invasions of New Zealand. 473 
in other words, is in general at or near the point of entry of the original 
species. Further, it is not necessary that the entry should be at a point. 
If it were, for example, by the whole zone from 300 to 700 miles, the 
resulting curve would be of the same type. 
Examination of the actual figures for the distribution of the New 
Zealand flora soon showed that every genus did in fact give a curve of this 
type, so that a fact of great significance was thus discovered, and one which 
may be considered without reference to the hypothesis of age and area, by 
whose assistance it was originally found. The distribution of the numbers 
followed two general types, as seen in the examples quoted below : 
Table I. 
0- 
-loom. 
1-200 
2-300 
3-400 
4-500 
5-600 
6-700 
7-800 
8-900 
9-1000 
10-1080 
Ranunculus . 
— 
2 
3 
5 
7 
11 
1 2 
18 
18 
10 
2 
Drimys . . 
2 
2 
2 
2 
2 
3 
3 
2 
1 
1 
1 
Pittosporum . 
. 11 
11 
11 
11 
8 
7 
6 
6 
5 
5 
1 
Colobanthus 
. — 
— 
— 
— 
2 
3 
3 
4 
2 
— 
Coprosma . . 
, 12 
12 
15 
16 
17 
18 
18 
16 
15 
12 
3 
Metrosideros 
. 8 
8 
8 
8 
5 
6 
6 
2 
1 
1 
1 
Ligusticum , 
. — 
i 
1 
1 
2 
7 
8 
9 
7 
6 
3 
Veronica . . 
6 
6 
10 
H 
39 ' 
4 1 
43 
38 
26 
2 
Utricularia . 
, 3 
3 
3 
1 
1 
1 
— 
— 
Pimelea . . 
4 
4 
5 
5 
7 
8 
8 
6 
5 
4 
1 
In all cases the figures show a maximum with a regular falling off, but in 
some, e.g. Pittosporum , the maximum is to the north, with no falling off to 
northwards, in others, e.g. Ranunculus , it is further south, with a falling off in 
both directions, and, as the examples chosen illustrate, the maximum may 
be at any zone from 5-600 to 8-900 miles. This phenomenon of a simple 
curve to a maximum (or two) is shown by every genus in the flora. 
These curves represent simply the naked unvarnished facts of taxonomic 
distribution, and they may be considered without reference to my hypo- 
thesis of age and area. It is quite clear from them that, for example, the 
previous distributional history of Pittosporum was different from that of 
Ranunculus or Veronica . And it is equally clear that in broad outline — 
which is all that we are as yet concerned with in taxonomic distribution — 
that distribution was not determined by biological agents, but by a more 
purely mechanical cause. 
Not only so, but it is also extremely difficult to believe that such regularity 
as this, and regularity of two types, would be shown as the result of casual 
arrivals across a wide expanse of water. It is hard to believe that it can be 
explained- — again in broad outline, and to the extent of say 90 per cent, of 
the flora — by anything but a previous land connexion of New Zealand with 
Indo-Malaya, and with other sources of flora. My critics, who frequently 
insist upon applying age and area to individual cases, force upon me the 
opinion that neither biological agencies nor casual distribution across the sea 
have had any hand in the present distribution of the New Zealand flora. 
