INSTINCTIVE BEHAVIOUR OF YOUNG BIRDS 95 
differentiation. But one must remember that in the case of 
the wasp there is no parental guidance ; the insect is more 
completely dependent on instinct than is the bird to whose 
needs the hen assiduously ministers. 
It is at first sight surprising that such birds as chicks and 
pheasants do not peck instinctively at still water. When a 
shallow vessel containing water was placed among some little 
chicks, several of them ran repeatedly through the water, but 
took no heed of it. Then, after about an hour, one of them 
standing in the vessel pecked at his toes, and at once lifted 
his head and drank freely with characteristic action. Another 
subsequently pecked at a bubble near the edge, and then he 
too drank. In fact, the best way of inducing them to drink 
is to scatter some grains of food in the tin; they peck at the 
grains, which catch their eye, and incidentally find the water, 
and the touch of water in the bill at once leads to the cha- 
racteristic response and congenitally definite behaviour. That 
the sight of a still surface does not itself suffice to evoke this 
behaviour is probably again due to the fact that under nature 
the hen guides them and pecks at the water, when they follow 
her lead. 
One fact which must be constantly borne in mind is that 
what is inherited is instinctive co-ordination, often related to 
a definite stimulus, not instinctive knowledge. A chick pecks 
at a grain when it is at a suitable distance, not because instinct 
provides him with the knowledge that this is something to be 
seized and tested, but because he cannot help doing so. He 
is so organized that this stimulus produces that result through 
an organic co-ordination that is independent of conscious 
knowledge or experience. How definite is the inherited co- 
ordination is shown by many observations. A young pheasant, 
only a few hours old, was taken from the incubator drawer, 
and held snugly while a piece of egg-yolk was moved before 
his eyes with the aid of fine forceps. He did not peck at it, 
but followed with movements of his head every motion of the 
object in a narrow circle. Simple as this action seems, it 
presents a striking example of co-ordinated movements 
