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KANSAS CITY REVIEW OF SCIENCE. 



are suspended from the upper end of the chrysahs, like the Danais; some with a 

 silken cord about the breast, like the Asterias, and others change 

 without being attached from any point. Some are smooth, oth- 

 ers have protuberances, some are notched and ringed, and some 

 knobbed. After a longer or shorter imprisonment, the chrysalis is 

 broken and the Imago escapes. The butterfly or moth, at first 

 limp and helpless, soon expands its wings, and fills one with won- 

 der that so much could be compressed in so small a space. There 

 is no other instance, probably, of such wonderful packing as the 

 case of a butterfly. 



When one reads of insect transformation merely, he knows but 

 little about the many things which combine and render perfect transformation pos- 

 sible. Not every egg is destined to reach the Imago. Indeed, the wonder is that 

 so many insects reach the perfect state. If the great number of eggs which the moth 

 lays is taken into consideration, we can readily see that, did all come to perfection', 

 s.uch an invasion as that of the army-worm of the present season is not only pos- 

 sible, but that myriads upon myriads of insects would cover the land. If, then, 

 the entomologist is annoyed when the chrysalis he has watched for months at 

 length develops into an ichneumon or other fly, or lies a hardened case, never to 

 open, or gives up at last, through some injury, an imperfect butterfly, let him re- 

 member the utter inundation there would be if all the eggs should reach perfec- 

 tion. 



I have sometimes wished, in looking at the elegant green house of the Dan- 

 ais, that it could remain, and not so soon have to be ruined by the issuing of the 

 Imago. A few weeks ago (June 1880) this wish was curiously gratified. I had 

 brought in two of the caterpillars of the Danais, [Fig. 4,] which, after eating for a 

 day or two, suspended themselves for their change. [Fig. 6.] 



Fig- 4- Fig. 6. 



Two days after I found one of them hanging limp and dead. I held my own 

 "inquest," aud decided he had committed suicide rather than bear the confine- 

 ment of his prison. The other had made his green and gold house. In a few 

 days more I saw below the chrysalis on the box-floor a Httle white maggot, which 

 changed into a brown pupa, and two others below the suspended caterpiller. At 

 once I noticed a small hole in the side of the chrysalis, and I knew the parasitic 

 fly had done its work. It was a case of arrested transformation and, fortunately 

 for me, arrested at precisely that stage which allowed the escape of the intruding 



