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ZOOLOGY 



out of it, clad in a new skin which had formed under- 

 neath. Caterpillars and reptiles are not the only 

 animals which change their skiris ; we do likewise, only 

 we do it gradually. Every time we wash our hands, 

 dead skin cells fall away imperceptibly and new ones, 

 formed underneath, take their place. The caterpillar 

 is the larva stage, the word "larva" applying to this 

 stage in any insect, "caterpillar" specifically to the 

 larva of one of the Lepidoptera. 



The pupa The caterpillar, becoming full fed, changes into a 



pupa, which may be exposed or in a cocoon, or may be 

 buried in the ground, according to the species. The 

 word "chrysalis" was applied to the pupa of certain 

 butterflies, which shine with a golden luster. From the 

 pupa emerges the moth or butterfly. The ancients, 

 observing how many larvae entered the ground and 

 remained apparently dead all winter, emerging as beau- 

 tiful moths next year, compared the adult or imago 

 with the human soul. The buried pupa of course sug- 

 gested the dead body, from which a perfect being should 

 emerge on the day of resurrection. 



Butterflies 2. The Lepidoptera are divided into several very dis- 

 tinct groups, of which the butterflies constitute one. 

 In the butterflies (Rhopalocera) the antennae are knobbed, 

 whereas in the moths they come to a point. In some 

 tropical groups this distinction is not perfectly clear, 

 so that disputes have arisen as to whether certain species 

 were butterflies or not. Commonly the butterflies are 

 also distinguished by the fact that they fly by day, 

 and when at rest hold the wings erect, one against the 

 other. Neither of these distinctions is reliable, how- 

 ever, since many moths are day fliers, and the manner of 

 holding the wings varies in both groups. The butterfly 

 pupa is not inclosed in a cocoon, as are those of many 



