158 BOYS AND GIRLS IN BIOLOGY. 



choose the leaves of the right one for her eggs. These 

 eggs are covered with a kind of glue which fastens 

 them to the leaf and keeps out the wet. You have 

 perhaps seen the "fairy bracelets" which are some- 

 times placed round the twigs of bushes. Fairies may- 

 wear these bracelets on state occasions, but the fairies 

 do not make them. They are the eggs of a moth laid 

 in a circle round the twig and fastened together with 

 glue. This bracelet is so strong that it will not break, 

 though you break the twig. It is astonishing how 

 much heat and cold these eggs will stand. They have 

 been known to live at a temperature of 200° Fahr., and 

 cold at 22° below zero will not kill them. The eggs 

 that are laid in the spring hatch very soon, those that are 

 laid in the fall do not hatch till spring. The last, like 

 the germ of the bean, take a long, long wintry sleep, 

 till the bright, warm, spring sun makes them open 

 their eyes. As soon as the caterpillar bursts his shell, 

 he begins to eat. He seizes upon the first thing that 

 comes in his way, which happens to be his egg-shell, 

 and this he devours most greedily. The whole end 

 and aim of his life seems to be to eat. The very first 

 day of his existence he eats up twice his own weight ; 

 so, of course, he must grow rapidly. At the end of one 

 month he weighs a thousand times as much as he did at 

 first, and, to make up this bulk, he has eaten forty thou- 



