3° 



The Study pf Animal Life 



insects which do no harm to the trees, but cleanse them 

 from injurious fungi. 



In many ways plants are saved from the appetite of 



animals. The nettle 

 has poisonous hairs ; 

 thistles, furze, and holly 

 are covered with spines ; 

 the hawthorn has its 

 thorns and the rose 

 its prickles ; some have 

 repulsive odours ; others 

 contain oils, acids, fer- 

 ments, and poisons 

 which many animals 

 dislike ; the cuckoo-pint 

 {Arum) is full of little 

 crystals which make our 

 lips smart if we nibble 

 a leaf. In our studies 

 of plants we endeavour 

 to find out what these 

 qualities primarily mean 

 to their possessors ; here 

 we think rather of their 

 secondary significance 

 as protections against 

 animals. For though 

 snails ravage all the 

 plants in a district ex- 

 cept those which are 

 repulsive, the snails are 

 at most only the second- 

 ary factors in the evolu- 

 tion of the repulsive 

 qualities. 



The strange inter-relations between plants and animals 

 are again illustrated by the carnivorous, generally insecti- 

 vorous, plants. It is not our business to discuss the 

 original or primary import of the pitchers of pitcher-plants, 



J. 4. — Acacia {A. s/']i<£roccphala), with hol- 

 low thorns in which ants find sliclter. 

 (After Schimper.) 



