THE FINCHES 85 



merely. With the law of correlated variation of parts as a known 

 factor in nature, this does not seem wholly impossible ; or a Darwinian, 

 who was also a believer in Lamarck's doctrine, 1 might explain the 

 facts by supposing that the ancestral crossbill, before it had become so 

 specialised, would, by perpetual endeavours thus to force the scales 

 open, have gradually made its bill crooked, so that the two tips ceased 

 at last to meet, from which point, if such a shape had not proved detri- 

 mental and we see that it did not the process of modification would 

 have continued. He might further surmise that such birds as could 

 not, by opening their mandibles a little, get them into a straight line, 

 to begin with, were placed at a disadvantage as against those who 

 could do so probably because the pronged bill would not enter the 

 sheath with facility and that thus the whole complicated structure 

 has at last come about. It is true that, as observed by Townson, 2 some 

 time before 1799, in his study at Gottingen, the crossbill, when actually 

 extracting the seed, grasps it (as I understand him to mean) between 

 the pointed tips of the mandibles. But can we suppose that, the pro- 

 tecting sheath being once forced open, the contents of it could not be 

 extracted with equal or sufficient facility, were the shape of the beak 

 normal ? Being as it is, it must be used as it is, but this may be the 

 resultant, rather than the cause. Still it is, perhaps, along these lines 

 of research that the true meaning of the abnormal curve may become 

 manifest The pointed tips might also be specially serviceable in the 

 tearing of the sheath to pieces, which the bird has sometimes even 

 now to resort to, but one does not gather clearly from the accounts of 

 observers 3 that this is the case. It is not, however, intended by these 

 remarks to do more than point out certain doubts and difficulties 

 which may still appertain to this ornithological problem. 



The abnormality of its beak is not the only way in which, from a 



1 I do not think this is exploded or can be exploded, however genial the experiments, in the 

 laboratory only, where the conditions of nature are not reproduced with sufficient accuracy. 

 Professor Francis Darwin, if I mistake not, has recently expressed himself as still in favour of 

 Lamarck's law, or, at least, as unconvinced against it- 



1 Tracts and Observations in Natural History and Physiology, 1799, p. 119. Before reading 

 Townson, I never could make out that any one had actually seen the lateral motion. 



3 E.g. Naumann, Naturgeschichte der Vogel Mitteleuropas, iii. 



