THE PROBLEM OF MAN'S ORIGIN 3 



set purpose, and for a very special reason which must be 

 briefly defined. 



Change comes about somehow in animal tj^pes, that 

 must be admitted, else there could be no groundwork 

 for the play of evolution. Change might conceivably 

 come about by " adaptation," and by that is meant the 

 reaction of the animal to its life surroundings. John 

 Hunter (1728-1793) had a clear conception of this in- 

 fluence, and his life work might be summed up by saying 

 that he saw, with the eye of a genius, the dependence of 

 structure on function. With the alteration of function 

 — not uncommonly as a result of change of environment 

 or habit — structure, in the individual, shows harmonious 

 change. 



As an inheritable, and so as an evolutionary, factor, 

 this adaptation of structure to function is especially 

 associated with the name of Jean Baptiste de Monet, 

 Chevalier de Lamarck (1744-1829), who, quite Hunterian 

 in his conceptions, appreciated to the full the influences 

 of " use and disuse " upon organs and systems. 



Changes, again, might be brought about, not by special, 

 definite, and purposive " adaptations," but by slight 

 " variations," and by " variations " we here mean those 

 trivial congenital differences, always displayed among 

 individuals, which are the progeny of parents possessing 

 varied individualities. Variation, aided by natural selec- 

 tion, constitutes that particular method of effecting change 

 in living things especially associated with the name of 

 Charles Darwin (1809-1882). By " sporting " or "muta- 

 tion " is understood, not a purposive adaptation, nor a 

 mere gradually accumulating minor congenital variation, 

 but the more or less sudden appearance of a " freak," if 

 one may so express it, among the offspring of an individual. 

 Evolution, by sporting or by mutation, is a more modern 

 conception, associated in the main with the name of De 

 Vries, and a^host of contemporary workers. 



These are ideas that are, or have been, current in 



