754 Letters, Extracts, and Notes. [Ibis, 



some of Colonel Meiiiertzliageii^s contentions about arti- 

 ficial breedino- and ''freakisli " 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 iu 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 tiiis docs 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, l)ut I take some exception 

 to his manner ot" 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 gi'oup 

 which at present do not lend themselves to experiment, 

 except iu 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 dift'erent theories ad- 

 vanced will be raised from the quicksand of a hypothesis to 

 the firm ground of demonstrated fact. 



Maud D. Haviland, H.M.B.O.U. 



Eesearcli Fellow in Zoology. 

 Newnhani College, 

 Cambridge, 



16 August, 1921. 



