134 Habit and Instinct. 



secondly, from the organs concerned in bodily movements ; 

 and, thirdly, from the heart, blood-vessels, skin, lungs, 

 glands, digestive organs, and so forth. Thus we have 

 (1) special sensations, (2) motor sensations, and (3) visceral 

 sensations, all of them experienced through the inter- 

 vention of incoming nerve-currents which reach the 

 higher brain-centres whose activity is accompanied by 

 consciousness. Now, in the case of the first peck, there 

 are, to begin with, the initiating sensations of sight; 

 and, secondly, the motor sensations due to the performance 

 of the act of pecking. There may be visceral sensations 

 as well, but these do not now concern us. When we 

 say, then, that the first peck, though it is an organic and 

 automatic response, nevertheless affords data to con- 

 sciousness, we mean that the act of pecking yields to 

 consciousness motor sensations already combined in 

 complex groups, and due to incoming currents from the 

 organs concerned in this particular kind of movement. 



A further statement of the matter from the physio- 

 logical point of view may serve to make the conception 

 clearer. We have seen that what is unquestionably 

 inherited, and what is, therefore, an essential feature in 

 all instinctive response, is motor co-ordination. A 

 stimulus gives rise to a commotion of some sort in the 

 cortical region of the brain, and this is accompanied by 

 sensation, say of sight. It also gives rise to a com- 

 motion in the lower brain-centres, or in some cases 

 those of the spinal cord, such as to cause the automatic 

 distribution of outgoing currents along efferent nerves 

 to certain motor organs, — those concerned, for example, 

 in pecking or in swimming. And these outgoing currents 

 are so nicely and delicately ordered and graded in intensity 

 as to produce just the particular movements required. 

 This is the inherited motor co-ordination, probably a 



