SUMMARY. 



Though it be true that dolus latet in generalibus, 

 it is a more important truth that " without premature 

 generalisations the true generalisation would never 

 be arrived at." * 



Therefore I conclude : — 



1. That Plasto-diethesis, or the moulding and 

 sifting processes experienced by organisms, 

 represents the beginning and end of higher 

 animal evolution ; and that its wide hyphen 

 stands for the provinces where Mendelism, 

 Mutationism, Tetraplasty, Orthogenesis, and 

 the dynamical work of growth on Form, as 

 well as other factors yet to be discovered, can 

 range at large. 



2. That personal selection is the leading form 

 of that process in higher animals, whereas 

 among Invertebrates, especially unicellular 

 forms, selection of groups is the rule. 



3. That Initiative in animal evolution comes by 

 stimulation, excitation, and response in new 

 conditions, and is followed by repetition of 

 these phenomena until they result in structural 

 modifications, transmitted and directed by 

 selection and the laws of genetics — a series of 



1 Herbert Spencer, Essays, II, 57. 



