NATURAL HISTORY STUDIES 



go on in green leaves, when, with the help of the 

 sunlight shining through a screen of chlorophyll, 

 they form complex stuffs like the starch of the potato 

 and the gluten of wheat out of the simple elements 

 of earth, water and air. 



On a second level are " reflex actions," which do 

 not require guidance or control, but depend on 

 inborn linkages of nerve-cells and muscle-cells, 

 which work when some outside cause pulls the 

 trigger, so to speak, or releases the spring. We 

 touch a hot iron, and without, in the strict sense, 

 willing it, we draw our finger away. A stimulus 

 has travelled up a sensory nerve to the spinal 

 cord, and a stimulus has passed down a motor 

 nerve to the muscles, commanding them to effective 

 action. This is a reflex action of a simple kind, 

 but there are elaborate activities and even parts 

 of industries which appear to be compound reflexes. 



On a third level are those activities which are 

 called instinctive. By which is meant that they are 

 performed in virtue of an inherited capacity ; 

 that they require no learning or experience, though 

 they are usually improved by both ; that they are 

 shared alike by all members of the species, or, at 

 least, by those of the same sex. Most animal 

 industries must be included here, though there is 

 sometimes a spice of intelligence intermingled in 

 their performance. The spinning of spiders, the 

 comb-building of bees, the paper-making of wasps, 

 the agricultural industries of ants, and so on, 

 seem to be, for the most part at least, instinctive. 

 The animals are, so to speak, hereditarily wound 



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