APPENDIX II. 



THE following paper by Dr. Fritz Miiller ' forms the 

 third of a series of communications on Brazilian butter- 

 flies published in " Kosmos," and as it bears upon the 

 investigations made known in the third essay of the 

 present work, I will here give a translation, by permis- 

 sion of the publisher, Herr Karl Alberts. 



" ACR^A AND THE MARACUjA BUTTERFLIES AS 

 LARVAE, PUP.E, AND IMAGINES. 



" In a thoughtful essay on ' Phyletic Parallelism in 

 Metamorphic Species,' Weismann has shown that in the 

 case of Lepidoptera the developmental stages of larva, 

 pupa, and imago vary independently, and that a change 

 occurring in one stage is without influence upon the pre- 

 ceding and succeeding stages, so that the course which 

 has been followed by the individual stages in their 

 developmental history has not been in all cases identical. 

 This want of agreement may manifest itself both by 

 unequal divergence of form-relationship, and by unequal 

 group formation. With respect to unequal form-diver- 

 gence the caterpillars are sometimes more closely related 

 in form than their imagines, and at other times the reverse 

 is the case. With respect to unequal group formation 

 again, two cases are possible ; the larvae and imagines 

 may form groups of unequal value, the one stage form- 



1 "Kosmos," Dec. 1877, p. 218. The paper is Ijere intro- 

 duced chiefly with a view to illustrate an important case of in- 

 congruence among Lepidopterous pupae. 



