120 THE LESSON OF EVOLUTION 



call it instinct. If a spider makes its web by 

 instinct, why should not the cells secrete the thread 

 by instinct ? If a gnat uses its wings by instinct as 

 soon as it is born, why should it not burst its larval- 

 skin by instinct ? Why should it not have formed 

 that skin by instinct '? And why should not its whole 

 development from the egg be due to the same cause ? 

 The gnat need not fly, he may die where he sits. 

 It is conceivable that he need not have broken out 

 of his larval-skin unless he wished to do so. But he 

 could not help developing from the egg, for that is 

 due to tissue-mind and is unconscious. The dif- 

 ference is that the animal has quite lost the power 

 of control over the older instincts, owing to the 

 number of times that they have been repeated. But 

 there is no difference in kind between those actions 

 and the exercise of conscious memory ; and it is im- 

 possible to draw a line between heredity and 

 instinctive action. Take for instance the origin of 

 fission. This, as I have already said, is a sanitary 

 provision, so that those pieces of protoplasm which 

 divided would be preserved by natural selection, 

 "while those which did not do so would perish. But 

 why should these pieces of protoplasm repeat the 

 process? It is not compulsory, for some pieces do 

 not divide. The only explanation is that the proto- 

 plasm remembered what it had done before, and did 

 the same again. And in time it got into the habit of 

 dividing. It is an instinct when the two pieces 

 are separate ; it is heredity when they remain 

 attached. 



Again, the fact that new variations are not always 



