ii6 THEORIES OF EVOLUTION 



that it would be impossible to explain evolution without 

 the Lamarckian Theory. 



Time will permit me to deal with only one class of 

 characters, a class associated with the nervous system 

 and manifested as instinct. These instinctiv^e actions 

 are general! \' thought to be the strongest evidence in 

 favour of Lamarckian Involution. It has been argued 

 that we cannot explain the instinctive action of aninials — 

 the wonderful instincts which are due, as we know, to 

 modifications of the nervous system, — except by supposing 

 that animals have intelligently modified their actions in 

 consequence of experience and observation, and that the 

 result has then been transmitted and has become the 

 non-intelligent instinct of their offspring. If we had no 

 other explanation of instinctive action, such an interpreta- 

 tion would constitute a strong suj^port to the Lamarckian 

 Theory. 



I do not, however, believe that this is the only, or, 

 indeed, the correct explanation of instinct. In consider- 

 ing this question, we must distinguish between the 

 instinct manifested l)y man)' of the higher invertebrate 

 animals and much that we are apt to call the instinct 

 of the vertebrates. A great many actions which are put 

 down to instinct in the higher vertebrates, such as birds 

 and mammals, are not instinctive at all, but the result of 

 intelligence. We see an example of this in the altered 

 behaviour of the seal which, as Nansen tells us, took up 

 a position on the outer ice-floes to escape the dangers of 

 the polar bear, and afterwards incurred this very danger 

 on the inner floes to avoid the greater peril from the 

 hunter. This is a clear case of intelligent association, 

 and no instinctive av^oidance of danger. So also with 

 a bird which Hies away if you have a gun in your hand, 

 but allows you to come near when you have a walking- 

 stick. This is the result of intelligence and not merely 

 instinct ; and we must carefully distinguish between 

 a lesson learned b}' the individual, however well learned 

 and easily repeated it may be. and a true instinctive action 

 which is never learned at all but springs fully formed 

 into existence. Such true instincts certainly occur in the 



