DIMOT^PHISM IN CHATTOrHOEUS ACERIS. 138 



of reproduction without waiting for tbeir final trans- 

 formation into the winged state. 



Again, the interesting economy of the Mexican 

 Axolotl has also a certain bearing on this subject. From 

 its outward appearance, this reptile. Prof. St. John 

 Mivart says, would be considered as an eft-tadpole, for 

 it has external branchiae or gills. As this creature 

 has, however, freely bred in confinement at Paris, in 

 the Jardin des Plantes, it has been regarded as adult, 

 and free from subsequent metamorphosis. Very un- 

 expectedly, however, and comparatively recently, these 

 Axolotls have undergone important changes in denti- 

 tion, and in an absorption of their external gills. 

 They have, in short, changed into an animal of a dif- 

 ferent genus, viz. Amblystoma, which singularly, in 

 addition to their change of form, have their reproduc- 

 tive organs atrophied and incapable. Thus, in a limited 

 sense, it may be said that as Axolotl is to the barren 

 Amblystoma, so is the sexual Chaitophorus to its 

 barren pseudomorph. There is nevertheless a differ- 

 ence in the analogy, inasmuch as Amblystoma is of a 

 higher type, but the pseudomorph of aceris certainly is 

 of a lower one. 



If we speculated upon the possibility that under 

 peculiar circumstances of growth these pseudomorphs 

 might be able to reproduce their kind, we should per- 

 chance find one clue towards the appearance of new 

 forms from dissimilar parents. According to the epi- 

 genetic hypothesis of Milne-Edwards and others, we 

 might then qualify the great dictum that " like pro- 

 duces like," and say that nature occasionally acts^er 

 saltum, as it were, and, " like then would produce un- 

 like," which may be thought a doctrine sufficiently 

 heretical, though perhaps, suggestive. 



