Plants in their Relation to Others. 
495 
Nor would the other popular theory, which equally survives to-day, 
satisfy the knowledge that I now had about local distribution. How could 
species be dying out in this remarkable chain-mail pattern, and why were 
there so many with small areas ? Had one perhaps arrived in Ceylon just in 
time to see the dying out of a considerable flora? And why did so many 
choose mountain-tops as a last resort ? If they had climbed from below, 
they must have plenty of adaptative capacity, and should be able to compete 
with the new-comers. Still more, why did each one or two choose a different 
mountain ? One had not credited plants with the animal desire to die in 
solitude, and it was difficult to believe that the plains were once inhabited 
by different species at every few miles, whilst many mountains with 
endemics did not even rise direct from the plains, but from a high plateau. 
Counting up all the species of the Ceylon flora, and dividing them 
into three groups — those endemic to Ceylon, those found only in Ceylon 
and South India, and those with a wider distribution abroad than this 
(which I termed wides for short) — I found ( 14 , 15 ) the endemics to be 
graduated downwards from few of large distribution area to many of small 
(e. g. Common 90, Rare 192), and the wides in the other direction (e. g. 
Common 4 62, Rare 159), with the Ceylon-South India species intermediate. 
In other words, the average area occupied by an endemic was small, that 
by a Ceylon-South India species larger, and that by a wide the largest of 
all. A cursory examination of other floras showed me that their endemic 
species also behaved in the same way, occupying overlapping areas, and 
I was at last furnished with what seemed to me to be a much more feasible 
explanation of the distribution of species in general, and endemics in 
particular. 
Having disposed, to my own satisfaction, of the notion that endemics 
were moribund species, I adopted the view that in Ceylon the wides were 
the first species (on the whole x ) to arrive, and had therefore on the whole 
occupied the largest areas. The Ceylon-South India species, on my view, 
must have arisen from them at points in general south of the middle of the 
peninsula, and would on the whole be younger in Ceylon than the wides, 
and therefore occupy lesser areas on the average. The Ceylon endemics 
would arise from the wides (or Ceylon-South Indians) in Ceylon, and would 
be the youngest, and on the average occupy the least areas. All the figures 
of course must be worked in averages, for an endemic of one group might 
be occupying a large area when the first wide of another arrived. 
Such in brief was the gradual evolution in my mind, during twenty 
years, of the hypothesis which I have christened ‘ Age and Area \ and which 
has been a good deal discussed of recent years. Before proceeding farther, 
I will quote the most recent expression of it, published in 1919 (22, 
p. 290) : 
1 i. e. in any genus the wide would usually be the first to arrive. 
K k 2 
