II.] 



INCIPIENT STRUCTURES. 



of conflicting tendencies would greatly favor their mutual 

 neutralization and obliteration if we may rely on the many 

 cases recently brought forward by Mr. Darwin with regard 

 to domestic animals. 



Mr. Darwin explains the imitation of some species by 

 others more or less nearly allied to it, by the common origin 

 of both the mimic and the mimicked species, and the conse- 



THE WALKING-LEAF INSECT 



quent possession by both (according to the theory of " Pan- 

 genesis ") of gemmules tending to reproduce ancestral 

 characters, which characters the mimic must be assumed 

 first to have lost and then to have recovered. Mr. Darwin 

 says, 15 " Varieties of one species frequently mimic distinct 

 species, a fact in perfect harmony with the foregoing cases, 



15 "Animals and Plants under Domestication," vol. ii., p. 351. 



