Ls) 
4 MR. ALFRED NEWTON ON THE POSSIBILITY OF 
even of the most carefully drawn-up lists. And yet, setting aside 
the immense difference there may exist between personal powers 
and opportunities of observation, to what two men will these phrases 
convey exactly the same meaning ? Now I confess I know not in 
what way such records can be reduced, so to speak, to a common 
standard, save by expressing them in figures ; nor how they can be- . 
come generally useful unless they are understood in one and the 
same sense. It is far from my wish to depreciate such observations, 
and I say this to guard against misapprehension.- Nay, I say 
more, if they are not taken for more than they are worth, they 
are highly useful ; but only as a basis for future and more complete 
inquiries. In their present state, as it seems to me, there is no 
denying that they are imperfect. To take, for instance, an ex- 
ample from that branch of Zoology of which I am least ignorant. 
A Devonshire and a Durham ornithologist in a local list of birds 
would probably each return Phyllopneuste trochilus and P. rufa 
as “common.” But were they to change places, the previous 
experience of each would, in a very short time, convince them that 
whereas, in the southern county, the latter species may double the 
former in numbers, in the northern the proportion might be ex- 
actly reversed. Now there are not very many people who have 
the chance of personally comparing for any sufficient time the pro- 
portionate numbers of the summer warblers on the banks of the 
Tamar and of the Tees. Besides, too, there is perhaps the natu- 
ralist resident perforce in Derbyshire who would fain institute a 
comparison between his own observations and those taken in 
Devonshire and Durham. The case becomes still more hopeless 
when we turn to foreign countries, and, referring to the duchy of 
Darmstadt or the province of Dauphiny, attempt to ascertain the 
relative abundance therein of the species I have named. 
Having thus briefly indicated the existing want of any such 
standard whereby local observations may be compared, I turn to 
the advantages which seem likely to follow the practical rendering 
of this suggestion. As chief among them (and the only one I will 
here adduce) I would place the light which might in consequence 
be thrown upon what we have lately heard so much of, the great 
question of the “ struggle for life.” It appears to me that 
before we can assign any cause for the predominance of any one 
species over another in any given district, the first thing to be 
ascertained is the measure of that predominance. This found, if 
the relative abundance of other species which influence its well- 
being—say, of insects or plants as affording it food and harbour, 
