208 FIELD AND HEDGEROW. 



will grow, but not beyond, just as if you had run a sepa- 

 rating ditch round the mountain. With the flora the in- 

 sects cease ; whether the germ comes from the vegeta- 

 tion or from the insect that frequents the vegetation 

 does not seem known. Still it would be worth while to 

 make a careful examination of the plant and insect life 

 just at the verge of the line of division. The bacillus 

 may spring from a spore starting from a plant or start- 

 ing from an insect. Most of England had an Alpine 

 climate probably once, and some Alpine plants and 

 animals have been stranded on the tops of our highest 

 hills and remain there to this day. In those icy times 

 English lungs were probably free of disease. Has formic 

 acid ever been used for experiments on bacilli ? It is 

 the ant acid ; they arc full of it, and it is extracted and 

 used for some purposes abroad. Perhaps its strong 

 odour is repellent to parasites. To return : while the 

 honey-bees live in comparative safety, the more or less 

 solitary wild bees have a great struggle to repel various 

 creatures that would cat them or their young, and, be as 

 watchful as they may, all their efforts at nest-building 

 arc often rendered nugatory by the success of a parasite. 

 So it is not worth while to catch them just for the pur- 

 pose of identification, for they have enough enemies in 

 the field without man and his heartless cabinets. The 

 collector is the most terrible parasite of all. Let them 

 go on with a happy hum, while the tulip opens in the 

 sunshine. 



