148 Mattingley, Principles Governing Movement \^ 



Jan 



entering the nest,* thus controlling and directing the course of the 

 ejectment and the other intermediary and dependent stimuli — in 

 fact, the whole metamorphoses. One can also follow the life- 

 history of the embryonic cell until its development to the parts 

 previously mentioned which control the organic and automatic 

 tendency, that is more fundamental than instinct, and which causes 

 the action of ejectment. As with other animals, birds are born 

 with permanent stimuli ; the legs to lever the body up or run with, 

 the beak to peck or grasp with, the wings as specially adapted levers 

 to flap or fly with. Permanent stimuli are often dependent on 

 secondary stimuli ; such as the unfledged wings of a bird, which 

 in their naked state are used as arms, and even legs, to assist in 

 bodily motion or propulsion (paleontology proves this), but when 

 provided with feathers of a proper size and weight and strength, 

 they, together with the naked arms, form a permanent stimulus 

 to fly. It is necessary to illustrate the contentions on which these 

 hypotheses are based. A very important and interesting observa- 

 tion mentioned is the adaptation of the back of the young Cuckoo, 

 hollowed out, as it were, apparently to assist it in ejecting the 

 young of its foster-parents, and it would be still more interesting 

 to know if all young Cuckoos in different parts of the world are so 

 adapted. But granting the adaptation of the back only goes to 

 prove that the operating factor which causes the young Cuckoo to 

 eject its nest-companions is not attributable to reason or instinct. 

 Were the young Cuckoo supplied with these powers it would be 

 quite unnecessary for nature to furnish the concavity in its back, 

 because the powers of reason or instinct would enable the Cuckoo 

 to effect the ejection of its nest-fellows. Probably one of the 

 strongest arguments is this : the young Cuckoo is blind at this stage ; 

 the nest is usually dome-shaped ; and how could it know which is 

 the opening of the nest from which to throw out its foster-brethren ? 

 It could not do it by sight. My hypothesis shows that it must be 

 due to the delicate nerves of the skin, guided by the different 

 temperature of the air or stimulus of light entering the opening of 

 the nest, indicating and directing the correct course. Then, again, 

 the young Cuckoo being blind, how could it tell when all the nest- 

 lings were out of the nest unless the skin coming no longer into 

 contact with the heated skin of its fellow-nestlings indicated this 

 fact to it. It is an axiomatic fact that nature is perfect in its 

 methods — how is it, then, that the visual organs, the organs nearest 

 the brain and the most important organs possessed by the bird, 

 are at this stage inoperative. The solution of this problem is that 

 Nature apparently finds the nerves of the skin are all that is neces- 

 sary to supply the correct stimulus to the brain. A bird's internal 

 organs digest its food whilst asleep — the stimulus of food causing 

 the digestive muscles to act without recourse to either the faculties 

 of instinct or reason. Is it too much to assume that the external 

 organs are endowed with equal powers to the internal organs ? 



* A douie-sliapcd, covciedin nest, with side eiiliance, 



