No. 580] ORIGIN OF SINGLE CHARACTERS 217 



cephaly of Cants. This opinion was formed in 1905 and 

 has in my mind been established by further research. 



It is, moreover, my theoretical view that rectigrada- 

 tions arise from some kind of germinal predisposition or 

 prepotency or potential homology. While the ' ' homology ' ' 

 or "homomorphy " uniting these new characters seem 

 to be due to some internal hereditary kinship between the 

 descendants of similar ancestors, their appearance is not 



spontaneous, but is invoked in some way connected with 

 similar bodily and environmental reactions which also we 

 do not at all comprehend. For certainly there is no evi- 

 dence that such " homologues " or "homomorphs" arise 

 from similar internal perfecting tendencies or teleologic 

 causes which operate independently of the reactions of en- 

 vironment and habit. 



The fact that certain rectigradations appear to corre- 

 spond with antecedent mechanical reactions in certain 

 cases, such as in the cuspules of the teeth, has led to the 

 opinion of Cope that these bodily mechanical reactions are 

 causative, but this opinion is completely offset by the fact 



