HAY-TIME 153 



times form a uniform sheet, or in other cases rows of 

 minute beads. The flinty covering prevents the 

 penetration of moisture, gives additional rigidity, and 

 perhaps defends the plant against the attacks of 

 certain animals. Some grasses are so effectually 

 protected that they are hardly ever eaten, but in other 

 cases the softer tissues especially are eaten out by 

 small, burrowing Insect-larvae. Browsing cattle dis- 

 regard such trifles as a microscopic layer of flint, 

 but even browsing cattle can be kept off by the 

 defences of certain common grasses. Nothing per- 

 haps is more effectual than a close covering of fine 

 hairs on the leaves and leaf-sheaths. These prevent 

 easy wetting, and the leaves become unpleasant to 

 chew. One reason why Holcus is avoided by cattle 

 is apparently that its leaves are hairy. 



How the grass-haulm is adapted to endure the 

 wind, how its proportions secure adequate strength 

 without waste of material, and how it comes to possess 

 such elastic stability that it sways beneath a light 

 breeze and yet is not prostrated by the storm, are 

 questions whose complete solution \vould I believe 

 exceed the powers of any mechanician. And the 

 problem might be further complicated to any extent 

 by taking into account the varying proportions of 

 different haulms, the varying loads which they have 

 to carry, and the minute structure of the hollow stalk, 

 which is far from homogeneous. Nature, working by 

 endless experiments, gives us a number of practical 

 solutions of questions which have actually come up for 

 settlement. She invites us to recover the question from 

 the answer, and to compare the practical with the 



