197 
Willis. — A<re and Area. 
CJ 
independently of Age and Area, but when analysed it appears that 
82 per cent, of the flora belongs to the more recent ‘ lowland ’ type, and has 
closely followed Age and Area in its distribution, while the remaining 
18 per cent, ‘are essentially arctic-alpine or boreal plants. These, as 
proved by the fossil record, are relics of a northern flora formerly more 
widespread, and a gradual elimination since glacial times has produced 
their present discontinuity of distribution.’ But if one were able to deter¬ 
mine the whole fossil record of these species, one would find, I have not the 
slightest doubt, that in their time of spreading they also followed Age and 
Area. Mrs. Reid, our leading palaeobotanist of the Tertiary, wrote to me 
about this paper, and allows me to quote the following sentence: 
‘ Mr. Matthews . . . has proved that, though Age and Area on the surface 
appears not to hold particularly well, it is not because it really fails, but 
because it is masked by a disturbing cause, and when that cause is dis¬ 
criminated and eliminated, there stands the law fully evidenced.’ 
In actual fact, the results of the Age and Area law maybe seen even on 
this receding highland flora, by working with larger areas, as is done below 
* 
in dealing with the flora of Dublin, where it is shown that the plants of this 
highland flora that occur in Dublin and Wexford can be mainly predicted 
from determining those that occur in Wales at corresponding distances from 
Duncansby Head. 
The general proposition put forward in Age and Area—that the area 
(sum of individual areas) covered by a group of ten or more allied species 
depends upon its age (sum of individual ages), whether within the country 
concerned, or (taking the whole world) from the time of its first evolution— 
is now being accepted by many biologists, but the further deductions which 
logically follow from its acceptance are still a bugbear to many, and I have 
myself come across two or three who say that they would accept Age and 
Area were it not for these inevitable sequels. 
The general standpoint taken up with regard to the relations of Age 
and Area to the theory of Natural Selection, which was set forth in very 
limited time at Hull, has been more fully elaborated in a paper in the 
‘ Nineteenth Century’ ( 12 ), to which reference may be made by those who 
desire a simple statement of the chief points of difficulty that Age and Area 
has brought up for the latter theory to surmount if it can. It has long been 
recognized that Natural Selection has only been repelling attack with greater 
and greater difficulty, and that it is hopelessly unable to explain the results 
of work upon Mendelian lines. Age and Area, which has opened a range of 
facts as widespread as those of Mendelism, and as inexplicable by Natural 
Selection, has thus brought a formidable attack to bear from a new quarter 
and with new forces. 
The acceptance of Age and Area, with its allied proposition of Size 
and Space, makes easily comprehensible many phenomena which have long 
