116 THE LESSON OF EVOLUTION 



Ten years previously to Hering's essay, 

 when Darwin was discussing phenomena 

 illustrating the problem of instinct, he had no 

 difficulty in shewing that a large number of them 

 were due to natural selection ; for useful habits are 

 selected as freely as useful structures. But, by a 

 most remarkable oversight, he thought that by doing 

 so he had destroyed the Lamarckian theory that 

 instincts are inherited habits, whereas he really 

 explained that theory. For new habits are due to 

 mental variations, and natural selection could have 

 nothing to do with them unless they were trans- 

 missible. Natural selection can develop habits into 

 instincts, provided they can be transmitted, but it 

 can no more originate a habit than it can originate* 

 a morphological variation. For habits arise from 

 ideas or sensations acting on the brain and causing 

 molecular rearrangements, which, by means of the 

 nerves and muscles, are transmuted into move- 

 ments. The next generation can only have the 

 same habit either by transmission or by imitation. 

 The elimination of the possibility of imitation is 

 the only difficulty in proving the physical trans- 

 mission of habits. 



I will select a few cases in which imitation is 

 impossible. When a new born baby breathes, cries, 

 and sucks, these actions cannot be due to imitation. 

 They are instincts which have been fostered by 

 natural selection ; but they originated as habits in 

 the Jurassic period, or before it. Many insects die 

 before their young are born, and yet the new 

 generation follows exactly in the footsteps of its 



