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 eariy 

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

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



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



