ON THK GENETIC VIKW oK NATL'HK. 331 



specially with the actual tact and the luiictiuii uf vaiia- 3i. 



'■ '' "Varia- 



tion ill the domain of living beings. He pushed the ^io"-" 



problem of variation and variability into llie foreground, 



and discussed one of its inaiii features — \\z., its possible 



etlect and results. Since his time the eye of every 



botanist, every zoologist, and every einl )ryologist has 



l)een directed towards the varialjility, transition, and 



genesis of forms, to their history rather than to their 



portraiture, whereas before him it was mostly attracted 



by their seeming fixity and recurrence. Variations have 



been studied on the large and on tlio minute scale in 



geological strata at home ami abroad, and the vexed 



question has been raised as to their causes and laws, — 



Darwin having been mainly occupied with their existence 



and operation, the results which they brought aV)0ut, the 



gradual alterations of the forms of living things. On 



this side he tells us that he found an important clue 



through reading a book which had appeared at the very 



end of the eighteenth century, Alallhus's ' Essay on the 



Principle of Population.' ^ 



arose as .simple varieties, and tliat | 1798, and in the enlarged and much 



the species of each genus were all | improved form in which it is now 



descended from a common ancestor ; I known in 1803. Darwin seems to 



but none of them ><ave a clue as to ' have come upon it accidentally. In 



the law or the method by which 

 the change had been effected. This 

 was still ' the great mystery ' " (p. 

 6). " Darwin, by his discovery of 

 the law of natural selection and his 

 demonstration of the great principle 

 of tlie preservation of useful varia- 

 tions in the struggle for life, lias 

 not only thrown a Hood of light on 

 the process of development of the 

 whole organic world, but also estab- 

 lished a firm foundation for all 

 futui-e studj- of nature " (p. 9). 



his Autobiography (' Life,' vol. i. 

 p. 83) he writes : " In October 1 838 

 — that is, fifteen months after I had 

 begun my systematic iuquirj- — I 

 happened to read for amusement 

 ' Malthus on Population,' and being 

 well prepared to apjireciate the 

 struggle for existence which every- 

 where goes on, from lonij-continued 

 observation of the hat>its of animals 

 and plants, it at once struck me 

 that under these circumstances 

 favourable variations would tend 



This essay apjieared first in ' to be preserved, and unfavourable 



