VI PREFACE. 



In 1844, the "Vestiges of Creation" appeared. The 

 author suggests that " impulses " were imparted to the 

 forms of life, on the one hand advancing them, and on 

 the other hand tending to modify organic structures in 

 accordance with external circumstances ; the effects thus 

 produced by the conditions of life being gradual. 



In 1852, Mr. Herbert Spencer " attributed the modifi- 

 cations [of species] to the change of circumstances." 



In 1859, "The Origin of Species" appeared. Mr. 

 Darwin did not at first seem to lay so much stress as 

 his predecessors upon the action of the environment as 

 a cause, for he says : " It is curious how largely my 

 grandfather, Dr. Erasmus Darwin, anticipated the views 

 and erroneous grounds of opinion of Lamarck." Again, 

 in speaking of the constancy of some varieties, he says, 

 " Such considerations incline me to lay less weight on 

 the direct action of the surrounding conditions, than on 

 a tendency to vary, due to causes of which we are quite 

 ignorant." * He had, however, previously said, " Changed 

 conditions of life are of the highest importance in 

 causing variability. ... It is not probable that vari- 

 ability is an inherent and necessary contingent under 

 all circumstances." f 



With regard to my own opinion, having been early 

 and greatly interested in Paley's "Natural Theology," 

 as well as the "Vestiges" when Mr. Darwin's work 



* Or. of Sp., p. 107. t I^id., p. 31. See also Desc. of Man, ii., p. 388. 



