EVOLUTION 931 



the lamb that is to be born. This was useful for her ancestors who 

 lived in rough places, but it is not needed on the modern sheep-farm. 



Instinctive Promptings — ^These two words give us the clue 

 to the whole matter. Think again of the "gimmer", that is to 

 say, a ewe that is about to lamb for the first time. She does not 

 know what is going to happen, but she obeys an inborn, hereditary 

 prompting to a certain routine of behaviour. It is quite easy to 

 prove that she does not understand what she is doing, for she is 

 often very much startled at the appearance of the lamb, and will 

 even run away afraid. But if she once licks the lamb there is an 

 instantaneous release of a series of maternal instincts, and she 

 allows it to suckle. Yet she does what she does, not because she 

 understands the situation, nor because of a recollection, but because 

 part of her inheritance is a series of instinctive promptings. There 

 are pre-established linkages between certain nerve-cells and certain 

 muscle-cells, and once the trigger is pulled the behaviour foUows. 

 No one is wise enough to say how soon or how far the creature 

 becomes aware of what it does, and how soon there are ripples of 

 emotion as well as nerve- thrills and muscle-contractions. But we 

 must try to understand that instinctive promptings are inborn or 

 hereditary, ready-made inspirations, which do not require any 

 learning or apprenticeship. They are as much part of the racial 

 inheritance as the convolutions of the brain, or the shape of the 

 teeth, the strength of the heart or the crinkliness of the hair. 



The Hand of the Past on Birds. — Darwin tells us of the 

 Musk-duck {Dendrocygna viduata), that in its native country and 

 wild state it often perches and roosts on trees, a very unusual thing 

 for a duck to do. Now it is very interesting that domesticated 

 Musk-ducks, though very sluggish birds, are fond of perching on the 

 tops of barns and walls. If allowed to spend the night in the 

 henhouse, the female will generally go to roost beside the hens, 

 though this may mean leaving the drake, who is too heavy to mount 

 so high. 



There is a significant old story of a race that was arranged between 

 a flock of domesticated geese and a flock of domesticated turkeys, 

 which were to be driven for miles along the highway. The farmer 

 who arranged the race put his money on the geese, and knowing 

 the habits of the two kinds of birds timed the contest so that the 

 turkeys would be passing under an avenue of trees about nightfall. 

 The turkeys were driven off at a great pace, and the geese lagged 

 behind. But it was a foregone conclusion in favour of the geese. For 

 when the turkeys reached the part of the road where there were 

 trees they flew up and roosted among the branches, whence they 

 could not be driven. The European turkey is in great part at least 



