340 PLANT-LIFE 



browsing animals. Prickles occur on tlie stems, the 

 midribs of the leaves, and the bracts of the flowers. 

 Insects, and even caterpillars, which try to reach the 

 flowers by way of the stem have to negotiate a whole 

 armoury of prickles, which usually baffle them. But it 

 also happens that the leaves arise from the stem in 

 pairs, their bases being united to form a species of cup 

 in which water collects. Insects thrust back by the 

 stem-prickles frequently tumble into the water and 

 get drowned. The Teazle is not beyond making use of 

 wastage; the macerated bodies of the insects appear to 

 make quite excellent broth, and this is absorbed by the 

 plant by means of strands of protoplasm, analogous to 

 root-hairs, which are extemporized in the leafy cup for 

 the purpose. The stems, leaves, and flower-stalks of 

 many plants are so hairy that, considering the size of 

 small insects in proportion to the length and arrange- 

 ment of the hairs, an attempt on their part to crawl 

 through them would be more than an equivalent of a 

 man striving to force a path through the dense jungle. 

 But we must not conclude that plant-hairs have no other 

 use than that just indicated; they have, indeed, a 

 greater significance, as we have before shown (p. 265). 



Either directly or indirectly animals depend upon 

 plants for food, so that in the very nature of things the 

 consumption of plants by animals is enormous — indeed, 

 incalculable. The supply of plants suitable for animal 

 feeding must be more than adequate to the demand ; no 

 matter how great the toll exacted on a species, if it is 

 to perpetuate its kind, it must always ensure a balance 

 to its own credit. The Diatoms (p. 28) consumed by 

 marine animals every day must be " as the sand on the 



