CH. I.] METAMORPHOSES OF INSECTS. 17 



caterpillar is ready to become a chrysalis, all the 

 parts of a butterfly may be discovered within its 

 body, thus satisfactorily proving that the chrysalis 

 is no more than " a beautiful and orderly represen- 

 tation of such limbs of the caterpillar as have grown 

 under its skin ; for though the limbs now mentioned 

 may be seen under the insect's skin at the time it 

 crawls and eats in the form of a caterpillar, never- 

 theless it is, in this state, on account of their ex- 

 treme tenderness and delicacy, a very difficult mat- 

 ter to have a satisfactory view of them. They are 

 in a manner as fluid as water, and they lie folded 

 up in many very tender membranes interwoven with 

 pulmonary tubes. The best time to obtain an ele- 

 gant view of them is when the caterpillar is just 

 about throwing off its skin, and exhibiting to open 

 view the miraculous operations of nature which it 

 hitherto concealed." 



In his remarkable history of " An Animal in an 

 Animal," the same author gives practical directions 

 as to the mode to be adopted to obtain a view of this 

 interesting sight : " one must choose a full-grown 

 caterpillar, tie to its body a small thread, and then 

 put it into boiling water, and take it out soon after ; 

 thus its external skin will separate, because the 

 fluids between the two skins are by this means rare- 

 fied and dilated, and therefore they break and separ- 

 ate both the vessels and the fibres wherewith they 

 were united together. By this means the external 

 skin of the caterpillar, being spontaneously separ- 

 ated, may be easily drawn off from the butterfly, 

 which is contained and folded up in it. This done, 

 it is clearly and distinctly seen, that within this skin 

 of the caterpillar a perfect and real butterfly was 

 hidden." 



These curious facts were illustrated by Swam- 

 merdam in the two following figures of the cater- 

 pillar of the tortoise-shell butterfly (Vanessa urtica), 

 in the second of which the outer skin has been drawn 

 B2 



