DEFENCES OF PLANTS 341 



seashore for number," yet, in spite of the myriads that 

 hourly disappear, there is no evidence of diminution; 

 the credit balance is as large as ever. That balance is 

 certainly due to a wonderful capacity for reproduction ; 

 Diatoms survive by force of numbers. And so must it 

 be with a goodly number of plants, especially those of 

 the humbler orders. The weight of Grasses eaten by 

 animals in the course of a year, could it be calculated, 

 would be discovered to be vast; yet Grasses survive, and 

 are nearly ubiquitous. Here we have not only increase 

 by seeds, but great vegetative activity and recuperative 

 power. If in summer-time we are to keep our lawns in 

 a condition pleasing to the zealous gardener, we must, 

 especially in warm, moist weather, run the mower over 

 them once, or perhaps twice, a week, so speedy and 

 vigorous is the growth of the grass. If, on the other 

 hand, the grass is dried and burned by a scorching sun, 

 it speedily becomes green after a good rain. Doubtless, 

 the vegetative possibilities and recuperative power of 

 Grasses constitute a most important factor in their 

 ability to more than survive the incursions of grazing 

 animals and the effects of drought. And, in addition 

 to having to supply grazing animals with a huge quantity 

 of food, Grasses have also to yield of their substance to 

 the appetites of numerous insect larvae. The larva of 

 the Tipula, or Crane-Fly, familiarly known as " Daddy- 

 Long-Legs," feeds underground on the roots of Grasses, 

 and does much damage : this larva is known to gardeners 

 and others as the " leather-jacket." 



But there are large numbers of plants that are avoided 

 by browsing animals, and there are some which they 

 would fain eat, but dare not. All these species are pro- 



