306 CELL INTELLIGENCE THE CAUSE OF EVOLUTION 



these structures, man, that produce them. In the case 

 of the caterpillar changing into a butterfly, the caterpillar 

 is entirely destroyed as an individual, but the builders 

 and material are still there and they take the same mate- 

 rial and with it build a new and different structure calcu- 

 lated to move through the air. Mr. Walker states that 

 there are various actions caused by the nourishment 

 which they obtain. The following are his ideas about 

 the cause : "Take the life history of a moth or butterfly, 

 as an example. A caterpillar hatches out of the egg com- 

 plete in all its parts and capable of looking after itself. 

 Directly it hatches out it simply grows in response to 

 the stimulus of nourishment. It does not require any 

 knowledge with regard to the kind of food which is neces- 

 sary for its well being; it is born with this knowledge, 

 When the next stage in its life-history arrives, it spins 

 itself a cocoon and that without ever having seen a co- 

 coon. This knowledge and skill is an inborn character 

 and the caterpillar is prompted to spin a cocoon at the 

 proper time, purely by instinct. When in the cocoon, the 

 caterpillar is metamorphosed into a chrysalis and in the 

 chrysalis all the parts of the perfect butterfly or moth 

 are developed simply by growth. When the butterfly or 

 moth hatches out in due course, all its muscles and organs 

 are developed and it is not dependent upon the stimulus 

 of use, that is of exercise in the case of the muscles, for 

 development." He states that it simply grows in re- 

 sponse to the stimulus of nourishment and that the but- 

 terfly or moth is developed simply by growth. Mr. 

 Walker has written what is considered to be a good up- 

 to-date work on the cause of heredity, but I do not agree 

 with him in the matter. He does not consider the cell 

 anything but a chemical force. There is nothing in life 

 that "simply grows." Everything is put together for a 



