:592 TENANTS OF AN OLD FARM. 



"I quite understand it now," said Abby ; "but I 

 am still at a loss to know how the pieces are put on. 

 Can you explain that ?" 



"In part at least ; for I have seen the process in 

 worms feeding upon arbor vita?. Take one example 

 which may illustrate others. In this drawing (Fig. 

 124) the worm has cleared a goodl}^ space around it 

 and has eaten along a twig toward the outer point. 

 Now, suppose that just wiiere its head is shown, 

 it cuts quite through the twig, whether by accident 

 or design I cannot say. Of course the outer part 

 drops down. But. while eating, the worm frequently, 

 quite constantly, indeed, spreads its viscid silk along 

 the leaf and so keeps it attached on both sides to 

 the upper edge of the sac, or to its own mouth- 

 parts. 



" Thus, the tip of the twig or leaf, when it is severed 

 from the stem, instead of falling to the ground, simply 

 drops alongside of the case to Avhich it is held by the 

 slight filament that attaches it to the sac, or as in 

 man}' instances, to the caterpillar's spinnerets. In 

 either case, the twig, leaf, stem, or cutting remains, 

 and after being drawn up, adjusted and tightened by 

 the w'orm, sticks tightly. As the creature is con- 

 tinually moving its spinning tubes around the top ot 

 the sac, these fastenings are continually being 

 strengthened. Thus one piece after another is added, 

 and so the basket grows. No doubt the animal varies 

 her mode of procedure, but so far as I have observed, 

 (he process is as I have given it. 



