16 NATURAL HISTORY. [CH. I. 



fifth and sixth segments, where there is a cavity or 

 gutter, in which it is easily kept from gliding back- 

 wards or forwards, and the cord is sometimes so 

 completely immersed in this channel as to be almost 

 hidden from sight. 



Although, as we have already stated, the newly- 

 formed chrysalis of a butterfly when opened is found 

 to contain only a mass of palp or soft substance, in 

 which no trace of the parts of the future butterfly 

 can be observed, yet we are able to perceive in the 

 external covering of the chrysalis all the external 

 organs of the fly, in a very short period before the 

 skin of the chrysalis has been cast off. Indeed 

 Swammerdam (whose inimitable dissections of va- 

 rious insects in their different states induced our 

 celebrated philosopher Ray, in his " Wisdom of God 

 in the Works of the Creation," to place him at the 

 head of those observers who had, by their exquisite 

 investigations, completely overturned the monstrous 



doctrine of equivocal generation) very plainly de- 

 monstrated, that even before the period when the 



