462 FACTORS OF ORGANIC EVOLUTION. 



domesticated animals and plants essentially depends npon this princi- 

 ple." In other words, certain differences are preserved through the 

 agency of natural selection, and certain differences are lost; if the 

 organism is removed from this restraining and directing agency, all 

 variations have the chance of asserting themselves. "All individuals 

 can reproduce themselves," Weismann explains, " and thus stamp their 

 characters npon the species, and not only those v.hicli are in all respects, 

 or in respect to some single organ, the fittest." I am convinced that 

 this term expresses a very important truth, and one which, as Weis- 

 mann says, is particularly apparent in domestic animals and plants; 

 but panmixia does not express an incident force. If new differences 

 arise in consequence of the cessation of the directive agency of natural 

 selection, it is because they were first impressed upon the organization 

 by some unaccountable agency; or, if there is simply a falling away 

 from accumulated characters, the residuary or secondary features which 

 appear are probably the compound and often deteriorated result of 

 various previous incident forces. In short, panmixia is a name for a 

 class of phenomena, and it can not be considered as itself an original 

 cause of variation. It is, to my mind, largely the unrestrained expres- 

 sion or unfolding of the growth-force consequent upou the removal of 

 the customary pressure under which the plant has lived. 



3. THE SURVIVAL OF THE UNLIKE. 



The one note of the modern evolution speculations which has 

 resounded to the remotest corner of civilization, and which is the chief 

 exponent of current speculation respecting the origin and destiny of 

 the organic world, is Spencer's phrase, "The survival of the fittest." 

 This epigram is an epitome of Darwin's law of natural selection, or 

 "the preservation, during the battle for life, of varieties which possess 

 any advantage in structure, constitution, or instinct." In most writ- 

 ings, these two i)hrases — "natural selection" and "the survival of the 

 fittest" — are used synonymously; but in tbeir etymology they really 

 stand to each other in the relation of process and result. The opera- 

 tion of natural selection results in the survival of the fittest. One 

 must not be too exact, however, in the literal application of such sum- 

 marj^ expressions as these. Their particular mission is to afford a con- 

 venient and abbreviated formula for the designation of important 

 I)rinciples, for use in common writing and speech, and not to express a 

 literal truth. Darwin was himself well aware of the danger of the lit- 

 eral interpretation of the epigram "natural selection." "The term 

 ^natural selection,'" he writes, "is in some respects a bad one, as it 

 seems to imply conscious choice; but this will be disregarded after 

 a little familiarity." This technical use Of the term " natural selec- 

 tion" is now generally accepted unconsciously; and yet there have 

 been recent revolts against it upon the score that it does not itself 

 express a literal principle or truth. If we accept the term in the sense 

 in which it was propounded by its author, we are equally bound to 



