CH. VII] CONFIRMATION BY PREDICTION 75 



explanation, as sound. The question now is to bring it into 

 accord with other views, theories, and facts, which often con- 

 flict with it, or apparently so. 



Summary 



This chapter is devoted to a few instances of the very suc- 

 cessful way in which Age and Area can be used to make pre- 

 dictions about distribution. For example, it was predicted— and 

 verified— that the outlying islands of New Zealand would have 

 a flora which was very old in New Zealand, and therefore very 

 widespread there. In fact it was found that on the average its 

 species ranged nearly 300 miles more in New Zealand than did 

 those that did not reach the islands. Further, those endemic 

 forms that reached the islands were found to be more widespread 

 in New Zealand than the species of its flora that reached Aus- 

 tralia, etc., but did not reach the islands— a result only explicable 

 by aid of Age and Area. Parallel results were obtained by a 

 study of the floras of various islands off the British coast, from 

 the Orkneys to the Sciflies. 



The reservations already laid down, that Age and Area must 

 only be applied to groups of at least teyi species, and to groups 

 of allied species, are then once more insisted upon. 



The successful prediction that as, on the Avhole, the larger 

 families and genera in a country will be the older, therefore the 

 flora of the outlying islands will be chiefly composed of these, is 

 then described. Other predictions indicate that the farther out 

 one goes the greater will be the proportion of wides, that the 

 outlying islands will have much in common, especially of large 

 genera in large families, that the endemics, both of New Zealand 

 and the outlying islands, will belong mainly to large families 

 and genera, and that most endemics will occur where there are 

 most wides. All these predictions proved successful, and as this 

 method has now been used over ninety times with no failures, it 

 is evident that Age and Area has strong foundations on which 

 to rest. 



