Appendix. 537 



ing higher or lower groups than the other, or they may 

 form groups of unequal size, i. e. t groups which do not 

 coincide but which overlap. Form-relationship and 

 blood-relationship do not therefore always agree ; the 

 resemblances among the caterpillars would lead to a quite 

 different arrangement to that resulting from the resem- 

 blances among the imagines, and it is probable that 

 neither of these arrangements would correspond with 

 the actual relationships. 



" Starting from this fact, which he establishes by 

 numerous examples, VVeismann proceeds to show most 

 convincingly that an innate power of development or of 

 transformation, such as has been assumed under various 

 names by many adherents of the development theory, 

 has no existence, but that every modification and ad- 

 vancement in species has been called forth by external 

 influences. 



" A most beautiful illustration of the want of ' phyletic 

 parallelism/ as Weismann designates the different form- 

 relationships of the larvae, pupae, and imagines, is fur- 

 nished by the five genera Acrcea, Heliconius, E.ucides, 

 Colamis, and Dionc (= Agraulis). This instance seems 

 to me to be of especial value, because it offers the rare 

 case of pupae showing greater differences than the larvae 

 and imagines. 



" The species of which I observed the larvae and pupae 

 are Acrcea Thalia and Alalia, Heliconius Eucrate, Encidcs 

 Isabella, Co/cents Dido and Julia, Dione Vanilla and 

 Juno ; besides these I noticed the pupa of Eueides 

 A lip her a. 



" The following remarks apply only to these species, 

 although we may suppose with great probability that the 

 whole of the congeneric forms excepting perhaps the 

 widely ranging species ofAcreea would display similar 

 characters to their Brazilian representatives. 



" The imagines of the five genera mentioned form two 



