140 THE JOURNAL OF BOTANY 
closely allied and almost simila: ; 
t the chief point which calls for notice is the theory pro- 
as an alien, e.., about docks), Ceterach, and Fragaria elatior, cases 
imilar? 
pounded in the introduction. «A species is only held to be native 
in a natural locality to which it has spread by natural means from 
a natural sour I e application of this theory to details, 
plants, which can be assigned to no Spot in the world as natives. 
- Dunn remarks, 
the only available point by which we can test status. A great pro- 
portion of the debateable part of the book therefore rests upon it. 
A second point, which recurs frequently and which is open 
to exception, is that of “outliers.” The case of Draba aizoides is 
€ 
Britain. But the Cotoneaster of the Great Orme supplies a very 
similar case, and it is surprising to find it placed among aliens 
of garden origin. The case of Aconitum Napellus is argued at some 
t the 
5 
length and decided adversely, partly on the ground. tha 
i found in Britain does in. tk 
in the parts of Europe nearest Britain, yet outliers are a perfectly 
ar omenon in botany, less eology. Un- 
accountable gaps often in distribution of plants, 
