X PREFACE. 



emphasis are just those which Mr. Darwin himself 

 latterly, though often indirectly perhaps, laid stress upon 

 in his experiments, viz. crossing, use and disuse, and the 

 physical conditions of life. 



In 1886, also appeared an article in Nature, entitled, 

 " Plants considered in Relation to their Environment." 

 It was not signed, but the author alludes to the external 

 conditions as bringing about all sorts of changes in the 

 vegetative system. He stops short of discussing floral 

 structures. 



In 1886, Dr. Vines' " Physiology of Plants" appeared. 

 After discussing various views and theories of reproduc- 

 tion, he observes, that " variability was first induced as 

 the response of the organism to changes in the conditions 

 of life." * . . . We conclude, then, that the production of 

 varieties is the result of the influence of the conditions 

 of life, t 



In the last page of his work. Dr. Vines calls attention 

 to Naegeli's view as follows : " Naegeli suggests, and his 

 suggestion is worthy of serious consideration, that there 

 is an inherent tendency to a higher organisation, so that 

 each succeeding generation represents an advance, ... as 

 in cases of what is termed saltatory evolution." Thus, 



* Page 676. Dr. Vines here uses almost identically the same words 

 as myself in 1881. I have just found that Mr. St. G. Mivart said much 

 the same in 1870, Genesis of Species, p. 269. See also 0. Schmidt's 

 Doctrine of Descent and Darwinism, p. 175. 



t Page 679. 



