142 DIFFICULTIES IN THE SYSTEM. 



This mode of arrangement, as might very readily 

 be proved by an induction from the particulars, after 

 we have obtained an outline of these, is borne out by 

 a regular gradation in all the leading habits of the 

 several races from the time that they leave the 

 shell till they become parents, and display those 

 instincts which complete their mature character 

 in the way in \vhich they provide for, or otherwise 

 treat their young. There are apparent anomalies in 

 such an arrangement, because at some parts of it 

 there seem blanks, where the characters of the one 

 division do not meet those of the next one so as to 

 preserve the continuity ; and there seem at other 

 places to be redundances, where two races, different 

 in some of their characters and habits, have others 

 so much in common or so equally, that it is not very 

 easy to say which ought, in strict propriety, to be 

 placed first. In some instances, these wants and 

 redundances, these breaks and doubles in the chain, 

 so to speak, exist only in our partial view of the 

 matter. But when we consider that birds, in one or 

 another of their varied tribes, inhabit the whole land 

 and sea, and that the characters of these are, in some 

 places, uniform over a considerable range, and in 

 others constantly varying ; that some are exuberantly 

 productive, and others bordering upon sterility ; we 

 may easily sec that the birds must crowd both in 

 species and in numbers to the places of abundant and 

 varied production, and be fewer and more uniform 

 where food is scanty and nearly all of the same 

 description. The natural series of birds is thus not 

 one which can proceed by uniformly equal distances 

 between race and race, but by distances varying 

 with the haunt, and the varying abundance of the 

 food for them, whether local or seasonal. Indeed, 



