261 
But it is not improbable that by the close of another period equal 
in length to the second the annual fall in the rate of introduction and, 
indeed, the annual rate of introduction itself will have become very 
small. 
There is not likely to be the same falling ofE in the rate of naturalis¬ 
ation of intentionally introduced species. For, as the Settlement extends, 
localities suitable for the spontaneous appearance of already introduced 
species become year by year more numerous and at the same time the 
number of species capable of naturalisation becomes increased. 
We find on briefly reviewing the results of our enquiry :— 
1. That the total number both of naturalised and of unintentionally 
inti’oduced species constantly increases. 
2. That the rate of naturalisation of intentionally introduced species 
has hitherto been lower than the rate of introduction of unintentionally 
introduced species. 
3. That in both cases the rate has been lower for the second period 
(1866-90) than for the first (prior to 1866). 
4. That this lower rate for the second period is more apparent than 
real, and is probably due as regards naturalised species to the survival of 
some cultivated species left to their fate when the early Settlement 
(1789-92) was abandoned, and as regards weeds to the fact that the 
greater number of common Indian weeds are necessarily introduced with 
the earliest sowings of grain. 
5. That in both cases the rate has now probably become nearly 
uniform, but that while for naturalised species it is steady or even uni¬ 
formly increasing, for weeds it is probably uniformly decreasing. 
The first three conclusions are borne out by the facts contained in 
the lists of species : the fourth is an expression of opinion, which it is 
unfortunately now impossible either to endorse or to refute as regards 
the Andamans ; it is, however, a question worthy of attention during the 
initial stages of any subsequent similar settlement: the last it will be 
easy for some future student of the subject to finally dispose of. 
In concluding, the writer wishes to express his great obligations to 
Col. Cadell, v. C., Chief Commissioner of the Andamans, but for whose 
kind assistance it would have been impossible to collect so many species 
during his short stay at Port Blair; also to Dr. Gr. King, f. r. s., c. i. b., 
for his kindness in supplementing the collection of 1889 with many 
specimens collected in April 1890. 
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