238 THE EFFECT OF TEMPERATURE 



forms, that is, which are nowhere to be found on the 

 earth at the present day, but which may have existed at 

 past epochs. Such a result may have been effected 

 through modification of temperature conditions hav- 

 ing taken place in the actual habitat of the species, 

 or from the species having migrated to a more southerly 

 or northerly region. The variety fiscberi of V. io, just 

 mentioned, is probably a phylogenetic form. The same 

 may be true of a variety rcederi of V. antiopa (Camber- 

 well Beauty), which Standfuss obtained by keeping the 

 pupae in a refrigerator. Again, exposure of the pupae 

 of V. atalanta (Red Admiral) to warmth, produced 

 specimens approximating towards V. callirrhoe and its 

 local forms, such as var. vulcanix, which are found in 

 the Canaries: i. e., to forms which may resemble the 

 common ancestor of these species. Other forms were 

 produced which may perhaps be destined to arise in the 

 future, in that they are further removed from the type 

 of related species, instead of approximating to them, like 

 the true phylogenetic forms. For instance, the widely 

 diverging specimens obtained in a few instances by the 

 action of warmth on V. antiopa, may belong to this 

 class. This variety has been named daubi by Stand- 

 fuss. 



(5) Finally, there is still a small unexplained residue 

 of modifications produced by temperature changes. 

 This possibly represents the direct reaction of the indi- 

 vidual species, completely independent of, and uncon- 

 trolled by, any inherited developmental tendency. 



It will be noticed that the principle of reversion is 

 called in by Standfuss to account for one of his five 

 groups, but Weismann, Dixey, Fischer, and others are 



