8 Proceedings. 



of cellulose, that both are made up of cells, and that those 

 parts of a plant which in the air produce epidermic hairs will 

 in water or in the earth develop root-hairs or fibres by which 

 that plant can be nourished. 



The second proposition I have to maintain is, that food- 

 nourishment or materials for supporting the growth of a 

 plant may be absorbed by the epidermis, and by its cellular 

 and hair-like extensions. The nourishment or plant-food 

 thus taken up is of two kinds, general and special ; the 

 former or general consisting of carbonic acid and ammonia, 

 as these are dissolved in the rain-water and dew which we 

 have shown to be taken up by superficial parts of plants ; the 

 latter or special food consists of nitrogenous matter derived 

 from insects and animalcules, or other living or dead animal 

 matter. This kind of food is only taken in by a limited 

 number of plants, called carnivorous or insectivorous. These 

 plants are fiu-nished with special organs for entrapping, 

 decomposing, and absorbing their insect-food. The food is 

 trapped in various ways. The Pitcher-plant is a well known 

 and very perfect example of one, but I prefer to adduce some 

 from the plants of our own neighbourhood. Take, for 

 instance, the Sun-dew {Drosera rotundifolia) growing on 

 Reigate Heath. Each leaf of this plant has above 100 hairs 

 growing on its upper surface. These hairs vary in length, 

 but they are so arranged that when curved inwards they form 

 an arch over the middle of the leaf. They are endowed with 

 great sensibility, and whenever a tiny insect alights upon 

 them they first entangle it by a viscid secretion which exudes 

 from the glandular head of the hau*, and then take away aU 

 chance of its escape by bending inwards so as to carry it 

 towards the middle of the leaf, where it is covered in the way 

 I have described. When an insect is caught in this way the 

 tentacles which surround it secrete a sort of gastric juice or 

 digestive liquid, which dissolves the nitrogenous matter in 

 the insect and fits it for the nourishment of the plant into 

 tissues of which it is to be absorbed. Another kind of trap 

 is seen in the Common Teasel [Dipsacus sylvestris). The 

 leaves of this plant from opposite sides of the stem are so 



