17£ ORIENTAL CHIMNEY SWALLOW. 



and also in Eastern Siberia, where, according to Pallas, 

 the Chimney Swallow has a remarkably rust-coloured 

 under side. As the different coloured birds pair together, 

 and as in the same nest there are to be found from 

 normal coloured parents — both colours — it is evident 

 that the varieties blend one with another, and as there 

 is very little difference in the forms and habits, so it 

 is not well to maintain that there is a difference of 

 species. But how is this question to be viewed? For 

 example as to climatic varieties? Our northern climate 

 has under some circumstances produced the African 

 form! No one can satisfactorily maintain that our 

 northern dark rust-coloured Chimney Swallow was 

 originally bred from the African! Nor can any one 

 connect the one in the climate of Egypt with that in 

 Eastern Siberia; far less can we deduce from the 

 casual fact of the varieties pairing together, that the 

 rust-colour of the Egyptian or Siberian Chimney Swallow 

 is due to physical causes. The name climatic variety 

 is only an arbitrary distinction." 



"Or races? But races can only be comprehended 

 with certainty within the same limits as climatic 

 varieties. The young will without any intermediate 

 form go back to that of the parents. Nature does not 

 carry out this idea precisely." 



"Perhaps sub-species? The comprehension of sub- 

 species is so little established in theory, and is so 

 variably demonstrated in practice, that it gives no 

 bounds to capriciousness." 



"In short, are local forms one and the same species? 

 But is not that a name without all philosophical or 

 physiological consideration? Perhaps all the better if 

 philosophy or physiology stood on weak ground. A 

 distinction founded on fact is at least remembered by 



