148 



SAGACITY AND MORALITY OF PLANTS. 



stemmed plants have no chance with them ; and 

 it is noticeable that the introduced and cultivated 

 plants in our gardens are more liable to their attacks 

 than wild species. We do not find the wild Roses 



Fig. 56. — Herb-Robert {Geranium. Rohertiaiiimt). Stems covered with hairs. 



of our lanes so thickly encrusted with strata of 

 plant -lice like those commonly observed on our 

 garden Roses. 



The crowded hairs on the stems of plants, as 

 well as the viscid secretions already mentioned, are 

 of great advantage to the species possessing them. 



