vin ORIGIN OF LIMBS 117 



whether the pelvis was a relic or only a rudiment you replied 

 that this was a question which nobody could answer. 



You seem to be quite sure now, and I think you are very 

 likely right. But I am not sure that I follow the argument that 

 limbs growing from the inside are inconceivable. As a fact they 

 may all arise externally. But the internal growth to meet the 

 external excrescence, and to support it, is in itself quite as difficult 

 to conceive as the opposite or reverse process. This is all a 

 matter of evidence as to fact, and not a question of greater or less 

 difficulty of conception. I do not know what amount of evidence 

 you have that hind limbs do always begin in internal appendages. 

 You can't get rid of the theoretical difficulty that every organ 

 must begin before it is fit for use ; and this applies equally to all 

 organs, whether they be internal or external. If all organic 

 beings have been developed gradually, there must be innumerable 

 specimens of incipient as well as of decaying structures. Yet 

 they never seem to be recognised or pointed out. 



PROFESSOR FLOWER TO THE DUKE OF ARGYLL 



39 LINCOLN'S INN FIELDS, W.C., 

 January 28, 1884. 



I will bear in mind your criticism about the limbs. There is 

 still much to be done in the way of working out their embryology 

 in detail. Balfour says, speaking of the elasmoid fishes, "The 

 two pairs of limbs appear as being the nearest to the parent stock 

 the youngest because the least aberrant from the original 

 mammalian type, so far as limbs are concerned. If so, how does 

 this doctrine apply to the appearance and development of whale- 

 bone as opposed to teeth? Clearly as regards them, the 

 whalebone whales are the most aberrant, the most differentiated, 

 from the original type. Whilst, as regards the limbs^ they are the 

 least differentiated, the least aberrant. 



You showed me some whale skeletons in which the whale- 

 bone was combined with teeth in full functional use, some in 

 which the whalebone was quite subordinate as regards use. Are 

 we to conclude that these are on the road to be full whalebone 



