I02 GENERATION OF INSECTS 



other hand, the argument that the worms enter from 

 without, is not to be waved aside, for it may be observed 

 that all the wormy filberts, from which the worm has 

 not already escaped, have a small hard projection on the 

 shell, that is perhaps the scar of the aperture made by the 

 worm when it was of small size, and working its way 

 through the soft shell of the nut, penetrated to its in- 

 ternal cavity; the aperture, after the shell grows and 

 hardens, closes, so that the worm, having grown, must 

 make another and larger hole when it wishes to escape, 

 which is indeed found in all filberts abandoned by the 

 worm. I am therefore in doubt what to believe, and 

 cannot come to a decision, although on the authority of 

 a very learned philosopher, I should be inclined to think 

 that the worms of filberts come from outside. This phi- 

 losopher is the famous Joachin Jung, of Liibeck, who re- 

 fers to this subject in his Memoranda on Physics, that 

 have been collected and printed with notes by Martin 

 Vogel, of Hamburg, a writer of great reputation, and a 

 friend of mine. 



The worms of the plum are similar to those of the fil- 

 bert, but they move more briskly and with greater speed. 

 They stay within the plum, where they are born, feeding 

 on the pulp and excreting, until they are perfectly grown, 

 when they abandon the fruit, and every worm builds 

 a small white cocoon of silk, from which it subsequently 

 issues in the form of a little gray butterfly having black 

 spots on the tips of its wings. The worms of the peach 

 and pear are of the same kind as those of the plum, and 

 make cocoons from which butterflies emerge. 



Perhaps the question may arise in your mind: are all 

 kinds of butterflies generated by trees, or do they come 

 from the parent through the stages of egg and worm? 



