A PERSISTENT PARASITE 



nut tree, where it lays its eggs in the growing nuts. 



" All species of animal life that change their shape 

 act in this way. In the first half of their existence, 

 under their initial form, they have certain habits 

 and certain dwelling-places; in the second half, un- 

 der their final form, they have habits and abodes 

 that are quite different. 



"Well, the worm that makes its home in the white 

 cells or granules of the diseased pig's flesh is also 

 subject to transformation. It has to change its 

 form, but before doing so it must first change its 

 abode. The cherry worm would never turn into a 

 fly so long as it remained in the cherry; the nut 

 weevil would never become a beetle if it continued 

 to abide in the nut. Both must emigrate and hollow 

 out a home for themselves in the earth if they would 

 cease to be worms and become a fly in one case, a 

 beetle in the other. In like manner, the parasites 

 of the diseased pig would never attain their final 

 form in the flesh that they inhabit; it is absolutely 

 necessary for them to change their abode in order 

 that the transformation may take place. But as 

 they cannot leave their cells of their own accord and 

 transport themselves to their new abode, which is 

 difficult of access, as you will see, they wait patiently, 

 whole years if necessary, for a favorable opportu- 

 nity to emigrate. ' ' 



1 ' Where then is this new abode ?'' ' asked Jules. 



"In us, my poor child, in us exclusively. The 

 cherry worm and the nut weevil are content, for the 

 purposes of their metamorphosis, with a hole in the 



