the Coloration of Eggs. 561 



are also possessed (as they may he) by Cuckoos that victimize 

 chiefly other birds than Weavers. 



The younger Cuckoo (I have not identified it) gave me 

 demonstration after demonstration of the gentle art of 

 evicting fellow-boarders of various kinds from even quite 

 deep nests, and/incidentally, of the use of the highly pre- 

 hensile feet in preventing himself from following them (as 

 he invariably did when he pushed them from the smooth 

 surface of my hand). The act of eviction is not a simple 

 hoist. There are many co-ordinated movements and an 

 exhibition of tenacity that may continue for ten minutes or 

 more, and that, through all the rests and demands for food 

 that punctuate a difficult operation, refuses, like a ratchet- 

 worked stump-lifter, to yield one millimetre of height 

 gained. The case is of much interest for its bearing on the 

 question of the origin of adaptations. It is impossible to 

 believe that the habit in its present complexity arose as a 

 single variation. If it did not, it is just as impossible to 

 believe that in its early stages it could have been selected — 

 at any rate in the newly-hatched bird ; for a miss is in this 

 matter as good as a mile, and there would have been nothing 

 at all but misses. One must invoke either the Lamarckian 

 explanation pure and simple, or (2) the supposition that the 

 habit was first selected in flat nests only (and this is in- 

 sufficient), or (3) suppose that it arose and was first selected 

 in nearly full-fledged birds and has passed back into an 

 earlier stage in development, being gradually perfected as it 

 did so — an interesting possible instance of the origin of an 

 instinct from, probably, a partly deliberate act. My present 

 Cuckoo viKS farouche in every sense of the word when I took 

 it, fuU-fledgedj from the nest. It threatened and attacked 

 myself with mouth displayed after the manner of an adult 

 at bay. It tolerated companions in the nest only so long as 

 they remained still. When they fidgeted or began to climb 

 on to itself it did not, like the younger Cuckoo, push under 

 them, drop its head, extend its legs, procure successive 

 purchases for its fcet^ and purposefully heave and hoist ; 

 but it showed irritability and sharply pushed or buffeted 



SER. X. VOL. IV. 2 q 



