754 Letters, Extracts , and Notes. [Ibis, 
some of Colonel Meinertzhagents contentions about arti¬ 
ficial breeding and u freakish ” varieties. 
As regards the statement on p. 532, it may be true of 
domesticated birds that “ no single artificial variety has 
ever, so far as we know, occurred in a wild state/’ but this 
is not the case for numerous species of plants, nor for other 
groups of animals. See, for instance, Tower’s observations 
on Leptinotarsa (Pub. Carnegie Inst. Washington, 1906). 
Tower’s work has been criticised on the ground that it is 
not certain that the strains he employed were pure— i. e. 
genotypes ; but this does not affect the value of his observa¬ 
tions as an argument against Colonel Meinertzhagen’s 
assertion, quoted above. 
I repeat that I have no desire to criticise Colonel 
Meinertzhagen’s views on subspecies, one way or the other. 
They may, or may not, be correct, but I take some exception 
to his manner of stating them, and still more to his method 
of founding conclusions on generalisations that are not 
always supported by facts. 
There are three methods by which, singly or in combina¬ 
tion, a scientific problem may be approached—induction, 
observation, and experiment; and, ultimately, it is only by 
experiment that a theory can be tested. Birds are a group 
which at present do not lend themselves to experiment, 
except in certain restricted instances; but because our 
experimental methods are inadequate, it is surely unreason¬ 
able to argue that all experimental work is unreliable, or 
that the facts themselves do not exist. 
I am unable to offer an opinion on the origin of species, 
owing to insufficient knowledge of the biological evidence 
necessary to form one ; but I am convinced that it will be 
only by experiment that any of the different theories ad¬ 
vanced will be raised from the quicksand of a hypothesis to 
the firm ground of demonstrated fact. 
Maud D. Havjland, H.M.B.O.U. 
Research Fellow in Zoology. 
Newnham College, 
Cambridge, 
16 August, 1921. 
