Introduction to Aur 41 



being those whose variations of forms are correlated to 

 their external conditions giving them the advantage 

 over their congeners. The offspring of each individual 

 usually inherit the parental peculiarities often intensi- 

 fied. Those that do not are (by hypothesis) at a dis- 

 advantage, and die off; hence permanent varieties, 

 sub-species, and species arise. When we bear in mind 

 that the physical conditions of nature in any place have 

 been highly variable, it gives a greater force to this 

 explanation of the method of variation.* This is J\Ir. 

 Darwin's theory of Natural Selection. As a natural 

 deduction from evolution, we have Dr. Hauglitoii s 

 law, that " all structures are arranged so as to give the 

 maximum of work possible under the given external 

 conditions," a law which is at the basis of the curious 

 study of Dysteleology,f for by its operation itj cuts 

 down all organs which, from altered external condi- 



* But while explaining the method, Natural Selection does not explain 



the cause. In artificial selection the cause is the presidcnce and direction 



of human intellect. In Natural Selection there is a necessity for predicating 



the existence of a prcsidence similar in kind, but grander in degree, as the 



changes effected by it are greater than those that artificial selection can 



accomplish. This evolution theory explains the tclcological correspondences 



noticed in animals, for by hypothesis the organ progresses according as the 



necessity for the function increases. Involution also is morphological that 



< >gress only along certain lines, and of this we can give no 



.nation, but can only say that it has been so that is, evolution has 



iinler law. 



is the study of rudimcntal and vanishing organs 

 distinguished from provisional organs, which arc 

 ;<><! of life, disappearing in otluTs. Rudimrnts 



may" '!y or only occasional!;. may 



unt of para-ilisin, &c., or vanishing heir- 

 f former 1- 



\ I 1 MI speaking of the 



w in gem i , as it test; : con- 



I [ erx'n.il \\ill. 



