78 SUDDEN APPEARANCE OF [Chap. X. 



for the intervals of time which have elapsed between our 

 consecutive formations, — longer perhaps in many cases 

 than the time required for the accumulation of each 

 formation. These intervals will have given time for 

 the multiplication of species from some one parent- 

 form : and in the succeeding formation, such groups or 

 species will appear as if suddenly created. 



I may here recall a remark formerly made, namely, 

 that it might require a long succession of ages to adapt 

 an organism to some new and peculiar line of life, for 

 instance, to fly through the air ; and consequently that 

 the transitional forms would often long remain con- 

 fined to some one region ; but that, when this adaptation 

 had once been effected, and a few species had thus 

 acquired a great advantage over other organisms, a 

 comparatively short time would be necessary to produce 

 many divergent forms, which would spread rapidly and 

 widely, throughout the world. Professor Pictet, in his 

 excellent Eeview of this work, in commenting on early 

 transitional forms, and taking bii'ds as an illustration, 

 cannot see how the successive modifications of the 

 anterior limbs of a supposed prototype could possibly 

 have been of any advantage. But look at the penguins 

 of the Southern Ocean ; have not these birds their front 

 limbs in this precise intermediate state of " neither true 

 " arms nor true wdngs " ? Yet these birds hold their 

 place victoriously in the battle for life ; for they exist 

 in infinite numbers and of many kinds. I do not 

 suppose that we here see the real transitional grades 

 through which the wings of birds have passed; but 

 what special difficulty is there in beKeving that it 

 might profit the modified descendants of the penguin, 

 first to become enabled to flap along the surface of the 



