ii ADAPTATION AND PROGRESS 107 



be something entirely different from a series of adapta 

 tions to circumstances, as mechanism claims ; entirely 

 different also from the realization of a plan of the 

 whole, as maintained by the doctrine of finality. 



That adaptation to environment is the necessary 

 condition of evolution we do not question for a 

 moment. It is quite evident, that a species would 

 disappear, should it fail to bend to the conditions of 

 existence which are imposed on it. But it is one thing 

 to recognise that outer circumstances are forces evolu 

 tion must reckon with, another to claim that they are 

 the directing causes of evolution. This latter theory is 

 that of mechanism. It excludes absolutely the hypo 

 thesis of an original impetus, I mean an internal push 

 that has carried life, by more and more complex forms, 

 to higher and higher destinies. Yet this impetus is 

 evident, and a mere glance at fossil species shows us 

 that life need not have evolved at all, or might have 

 evolved only in very restricted limits, if it had chosen 

 the alternative, much more convenient to itself, of 

 becoming anchylosed in its primitive forms. Certain 

 Foraminifera have not varied since the Silurian epoch. 

 Unmoved witnesses of the innumerable revolutions 

 that have upheaved our planet, the Lingulae are to-day 

 what they were at the remotest times of the paleozoic 

 era. 



The truth is that adaptation explains the sinuosities 

 of the movement of evolution, but not its general 

 directions, still less the movement itself. 1 The road 

 that leads to the town is obliged to follow the ups and 



1 This view of adaptation has been noted by M. F. Marin in a remark 

 able article on the origin of species, &quot; L Origine des especes &quot; (Re&amp;lt;vue 

 icientifique, Nov. 1901, p. 580). 



