79 



Perhaps the same sort of mechanism is used eren by 

 those caterpillars which da not appear to be hairy. 

 For they really are so, as the microscope shews. When 

 the upper skin of one just ready to change, is slit 

 longitudinally in the place where the crack would be, 

 the skin may be taken off, and it is easily seen how (he 

 new one lies below. The hairs are disposed in the ni- 

 cest manner, for lying smooth under the upper skin : 

 they grow in separate tufts, which never lie one upon 

 another, but together form one surface. 



It is remarkable, that immediately after this change, 

 they appear much larger than they did before ; and 

 they really are so. The very head and skull are great- 

 ly larger than before the change. The operation of 

 the cray- fish in changing it< slu v il may explain this* 

 This also is found considerably larger when out of the 

 shell than before. In both cases, the body had grown 

 so much, that it was too big for its covering. How- 

 ever, while it remained in it, the parts were compres- 

 sed, and forced to lie in that narrow room. But as 

 10011 as that covering is off, every part distends itself 

 to its proper size. 



Indeed, so large a skull, being a hard substance in 

 the caterpillar, could f.ot have been compressed into 

 a smaller ; but the fact is, the new skull never hardens 

 till the change approaches, and then imperfectly. At 

 the same time it necessarily takes, from the place it is 

 ID, an oblong form. In this shape it is found a fevv 

 hours before the old skin is cast off, not enclosed with* 

 in it, but extended under the skin of the first ring of 

 the body. When the old skull is thrown oft, the new- 

 one soon hardens, and takes its' proper figure. 



We call the creature hatched from the egg of a but- 

 terily, a caterpillar; but it is a real butterfly a 1 that 

 time. A caterpillar changes its skin four or live times, 

 and when it throws off one, appears in anoiher of the 

 same form ; but when it throws off the . ! a;t, as it is now 

 so perfect as to need no farther nourishment, so there 

 is no farther need of teeth, or any other parts of a 

 caterpillar. 



4 



