CHAPTER V 



SENSITIVE PLANTS 



One of the first caterpillars that we find in our 

 gardens in the early spring is that of the familiar 

 brown ^' woolly bear," the larva of the tiger moth. 

 When we see this insect infant feeding on our 

 plants, we only need to touch it with a finger to 

 cause it immediately to become a hairy ball which 

 at once drops to the ground. We may then try to 

 pick it up from amongst the herbage below, but its 

 long flexible hairs give way so readily to the touch, 

 and are so often left in our fingers that not infre- 

 quently the caterpillar escapes by means of these 

 defensive tactics ; for leave it alone for a minute or 

 two and it quickly unrolls its body and travels 

 aw^ay at a surprising pace out of the danger zone. 



There is nothing astonishing in the fact that the 

 caterpillar thus shrinks at our touch. It is as 

 natural as that a hedgehog which we might meet 

 in the lane should assume the defensive and be- 

 come a prickly ball when we poke it with our 

 walking-stick. It is obvious to us, when we 

 touch the hairs of the caterpillar or the spines of 

 the hedgehog, that these creatures are sensible of 

 the touch ; and it is apparent that the subsequent 

 actions of both caterpillar and hedgehog are defen- 

 sive. This sensitiveness, therefore, by prompting 



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