128 J. HOPKINSON ANNIVEESAEY ADDRESS : 



The attempt to account for the origin of life from an aqueous 

 Solution acted on by an electric current was the greatest flaw in 

 the work of Chambers, and he erred in many points, especially in 

 deriving the mammals from the birds, their pedigree being from 

 the fishes through the amphibians; yet he certainly prepared the 

 way for the reception of Darwin's theory, as Darwin himself 

 acknowledges, for the ' Vestiges ' had a large sale and gave rise to 

 a very extensive controversy. But, without the principle of natural 

 selection, no theory of evolution could be satisfactory. 



The fundamental principles of the origin of species by means of 

 natural selection are thus stated by Darwin: — "As many more 

 individuals of each species are born than can possibly survive ; and 

 as, conseqiiently, there is a frequently -recurring struggle for exist- 

 ence, it follows that any being, if it vary however slightly in any 

 manner profitable to itself, under the complex and sometimes 

 varying conditions of life, will have a better chance of surviving, 

 and thus be naturally selected. From the strong principle of in- 

 heritance, any selected variety will tend to propagate its new and 

 modified form." 



These principles may perhaps be more clearly apprehended if 

 stated in a somewhat different manner, and slightly modified and 

 elaborated. 



1. In every species many of the offspring do not attain 

 maturity, owing to all living things being perpetually engaged 

 in a struggle for existence. 



2. Few, if any, animals or plants are exactly alike in all 

 respects at any stage of their existence. 



3. However slightly one individual may differ from another, 

 if the variation gives one a better chance of living than the other, 

 that one will be the most likely to survive. 



4. External conditions vary from time to time, the alteration 

 usually being gradual and progressive, 



5. If in any species some of the offspring differ from the 

 parent in any way which makes them more suited to new 

 conditions than the offspring which more nearly resemble the 

 parent, they will have the best chance of living. 



6. Any beneficial variation in the offspring will most probably 

 be transmitted to their offspring ; and if the external conditions 

 then remain the same, or if they continue to change in the same 

 direction, this variation will be perpetuated. 



7. A new variety, better adapted for new conditions than the 

 normal form, may, and in the struggle for existence most probably 

 will, oust the normal form, which will gradually die out. 



