572 Professor C. Lloyd Morga7i [Jan. 28, 



So much for our general scheme. If now we turn to the instinctive 

 behaviour concerned in locomotion, we find a congenital basis upon 

 which the perfected activities are founded. There is on the part of 

 the chick no elaborate process of learning to walk ; ducklings and 

 moorhens a few hours old swim with perfect ease when they are 

 placed in water ; these birds also dive without previous practice or 

 preliminary abortive attempts ; while young swallows, if their wings 

 are sufficiently large and strong, are capable of short and guided 

 flights the first time they are committed to the air. In these cases 

 neither the internal impulse nor the sensory stimuli are so well 

 defined as in that of the nutritive activities. The impulse probably 

 takes the form of an uneasy tendency to be up and doing, perhaps due 

 to ill-defined nervous thrills from the organs of locomotion, which are 

 in need of exercise. The sensory stimuli are presumably afibrded by 

 the contact of the feet with the ground or with the water, and by the 

 pressure of the air on the wing surfaces. It is a curious fact that if 

 joung ducklings be placed on a cold and slippery surface, such as 

 that of a japanned tea tray, they execute rapid scrambling movements 

 suggestive of attempts to swim, which I have never seen in chicks, 

 pheasants or other laud birds. 



It will not be supposed that I claim for perfected locomotion, so 

 admirably exemplified in the graceful and powerful flight of birds, an 

 origin that is wholly instinctive and unmodified by the teachings of 

 experience. Here, as elsewhere, instinct seems to form the ground plan 

 of activities, which intelligence moulds to finer and more delicate 

 issues. This is the congenital basis on which is built the perfected 

 superstructure. And if our opjjortunities for observation and our 

 methods of analysis were equal to the task, we should be able to dis- 

 tinguish, in the development of behaviour, the congenital outline from 

 the shading and detail which are gradually filled in by the pencil of 

 experience. 



The difficulties which render this analysis at the' best imperfect 

 are therefore twofold. In the first place, intelligence begins almost 

 at once to exercise its modifying influence ; and in the second place, 

 many instinctive traits do not appear until long after intelligence has 

 begun its work. Much of the intelligent detail of the living picture 

 is filled in before the instinctive outlines are complete. The term 

 *' deferred instincts " has been applied to those congenital modes of 

 procedure which are relatively late in development. The chick does 

 not begin to scratch the ground, in the manner characteristic of rasorial 

 birds, till it is four or five days old, nor does it perform the operation 

 of sand- washing till some days later ; the moorhen does not begin to 

 flick its tail till it is about four weeks old ; the jay does not perform 

 the complex evolutions of the bath till it has left the nest and felt its 

 legs, when the stimulus of water to the feet, and then the breast, 

 seems to start a train of acts which, taken as a whole, are of a remark- 

 ubly definite type. The development of the reproductive organs brings 

 with it, apart from the act of pairing, a number of associated modes of 



