82 



ANIMAL MECHANISM. 



tlie surprising variety of living beings, has already furnished 

 important arguments in favour of development. But many 

 savants look with suspicion on these studies ; they consider 

 that the immutability and variability of animal species belong 

 to the domain of insoluble questions. 



It is true, that if we ask the partizans of development to 

 prove experimentally the reality of their doctrine ; if we 

 require of them, for example, to transform the ass species into 

 the horse or anything analogous to it, they are forced to avow 

 their inability, and they reply that it is necessary, in order 

 to effect this, to exercise modifying influences during millions 

 on millions of years. It must indeed have been by very slow 

 transitions that the variation of species has been effected, if it 

 indeed has taken place. Consequently, in the absence of an 

 experimental solution, the development hypothesis can neither 

 be proved nor refuted. 



Learned men, whose minds are habituated to rigorous de- 

 monstration, are not interested in such questions ; they have 

 no scientific value in their estimation. And yet science meets 

 with such every day. When an astronomer studies the in- 

 fluences which may cause the heavenly bodies to move more 

 slowly ; when he predicts a modification of the orbit of the 

 earth after the lapse of some millions of years, or a lengthen- 

 ing of the period of rotation of our planet— changes which 

 would affect all the inhabitants of the earth with a mortal 

 chill — this philosopher is listened to. When he speaks of a 

 cause, however slight it may be, of the retardation of a 

 planetary movement, every one understands that if this cause 

 should continue during many ages, its effects will be exag- 

 gerated by the lapse of time. No one tells this astronomer 

 to wait till some millions of years have proved the accuracy of 

 his reasonings. 



Why should we be more unjust to the theory of develop- 

 ment ? It cannot, it is said, bring before our eyes the trans- 

 formation of one animal into another. This is true, but it 

 may show us some tendency to this transformation. However 

 slight it may be, yet accumulating more and more during 

 many ages, it may become as complete a transformation as 

 we can imagine. 



